diff --git a/lib/db/install.xml b/lib/db/install.xml
index e18b9a07e03..4db36cf9eae 100644
--- a/lib/db/install.xml
+++ b/lib/db/install.xml
@@ -4610,6 +4610,9 @@
         <KEY NAME="usercreated" TYPE="foreign" FIELDS="usercreated" REFTABLE="user" REFFIELDS="id"/>
         <KEY NAME="usermodified" TYPE="foreign" FIELDS="usermodified" REFTABLE="user" REFFIELDS="id"/>
       </KEYS>
+      <INDEXES>
+        <INDEX NAME="report-filter" UNIQUE="true" FIELDS="reportid, uniqueidentifier, iscondition"/>
+      </INDEXES>
     </TABLE>
     <TABLE NAME="reportbuilder_audience" COMMENT="Defines report audience">
       <FIELDS>
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index ffc4baecee5..6dc52e62102 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -3471,5 +3471,35 @@ privatefiles,moodle|/user/files.php';
         upgrade_main_savepoint(true, 2023082200.02);
     }
 
+    if ($oldversion < 2023082200.04) {
+
+        // Remove any non-unique filters/conditions.
+        $duplicates = $DB->get_records_sql("
+            SELECT MIN(id) AS id, reportid, uniqueidentifier, iscondition
+              FROM {reportbuilder_filter}
+          GROUP BY reportid, uniqueidentifier, iscondition
+            HAVING COUNT(*) > 1");
+
+        foreach ($duplicates as $duplicate) {
+            $DB->delete_records_select(
+                'reportbuilder_filter',
+                'id <> :id AND reportid = :reportid AND uniqueidentifier = :uniqueidentifier AND iscondition = :iscondition',
+                (array) $duplicate
+            );
+        }
+
+        // Define index report-filter (unique) to be added to reportbuilder_filter.
+        $table = new xmldb_table('reportbuilder_filter');
+        $index = new xmldb_index('report-filter', XMLDB_INDEX_UNIQUE, ['reportid', 'uniqueidentifier', 'iscondition']);
+
+        // Conditionally launch add index report-filter.
+        if (!$dbman->index_exists($table, $index)) {
+            $dbman->add_index($table, $index);
+        }
+
+        // Main savepoint reached.
+        upgrade_main_savepoint(true, 2023082200.04);
+    }
+
     return true;
 }
diff --git a/reportbuilder/classes/local/helpers/report.php b/reportbuilder/classes/local/helpers/report.php
index 7ee0a080265..b979443896e 100644
--- a/reportbuilder/classes/local/helpers/report.php
+++ b/reportbuilder/classes/local/helpers/report.php
@@ -110,6 +110,7 @@ class report {
     public static function add_report_column(int $reportid, string $uniqueidentifier): column {
         $report = manager::get_report_from_id($reportid);
 
+        // Ensure column is available.
         if (!array_key_exists($uniqueidentifier, $report->get_columns())) {
             throw new invalid_parameter_exception('Invalid column');
         }
@@ -237,10 +238,16 @@ class report {
     public static function add_report_condition(int $reportid, string $uniqueidentifier): filter {
         $report = manager::get_report_from_id($reportid);
 
+        // Ensure condition is available.
         if (!array_key_exists($uniqueidentifier, $report->get_conditions())) {
             throw new invalid_parameter_exception('Invalid condition');
         }
 
+        // Ensure condition wasn't already added.
+        if (array_key_exists($uniqueidentifier, $report->get_active_conditions())) {
+            throw new invalid_parameter_exception('Duplicate condition');
+        }
+
         $condition = new filter(0, (object) [
             'reportid' => $reportid,
             'uniqueidentifier' => $uniqueidentifier,
@@ -317,11 +324,16 @@ class report {
     public static function add_report_filter(int $reportid, string $uniqueidentifier): filter {
         $report = manager::get_report_from_id($reportid);
 
-        $reportfilters = $report->get_filters();
-        if (!array_key_exists($uniqueidentifier, $reportfilters)) {
+        // Ensure filter is available.
+        if (!array_key_exists($uniqueidentifier, $report->get_filters())) {
             throw new invalid_parameter_exception('Invalid filter');
         }
 
+        // Ensure filter wasn't already added.
+        if (array_key_exists($uniqueidentifier, $report->get_active_filters())) {
+            throw new invalid_parameter_exception('Duplicate filter');
+        }
+
         $filter = new filter(0, (object) [
             'reportid' => $reportid,
             'uniqueidentifier' => $uniqueidentifier,
diff --git a/reportbuilder/tests/external/conditions/delete_test.php b/reportbuilder/tests/external/conditions/delete_test.php
index 9ef9bbc6e78..dc236aac8f0 100644
--- a/reportbuilder/tests/external/conditions/delete_test.php
+++ b/reportbuilder/tests/external/conditions/delete_test.php
@@ -84,7 +84,7 @@ class delete_test extends externallib_advanced_testcase {
         /** @var core_reportbuilder_generator $generator */
         $generator = $this->getDataGenerator()->get_plugin_generator('core_reportbuilder');
 
-        $report = $generator->create_report(['name' => 'My report', 'source' => users::class]);
+        $report = $generator->create_report(['name' => 'My report', 'source' => users::class, 'default' => false]);
         $condition = $generator->create_condition(['reportid' => $report->get('id'), 'uniqueidentifier' => 'user:email']);
 
         $user = $this->getDataGenerator()->create_user();
diff --git a/reportbuilder/tests/external/conditions/reorder_test.php b/reportbuilder/tests/external/conditions/reorder_test.php
index bb0a5e648a9..f87513d7893 100644
--- a/reportbuilder/tests/external/conditions/reorder_test.php
+++ b/reportbuilder/tests/external/conditions/reorder_test.php
@@ -92,7 +92,7 @@ class reorder_test extends externallib_advanced_testcase {
         /** @var core_reportbuilder_generator $generator */
         $generator = $this->getDataGenerator()->get_plugin_generator('core_reportbuilder');
 
-        $report = $generator->create_report(['name' => 'My report', 'source' => users::class]);
+        $report = $generator->create_report(['name' => 'My report', 'source' => users::class, 'default' => false]);
         $condition = $generator->create_condition(['reportid' => $report->get('id'), 'uniqueidentifier' => 'user:email']);
 
         $user = $this->getDataGenerator()->create_user();
diff --git a/reportbuilder/tests/external/conditions/reset_test.php b/reportbuilder/tests/external/conditions/reset_test.php
index 1538583c1ba..de423e2a5f7 100644
--- a/reportbuilder/tests/external/conditions/reset_test.php
+++ b/reportbuilder/tests/external/conditions/reset_test.php
@@ -49,7 +49,7 @@ class reset_test extends externallib_advanced_testcase {
 
         /** @var core_reportbuilder_generator $generator */
         $generator = $this->getDataGenerator()->get_plugin_generator('core_reportbuilder');
-        $report = $generator->create_report(['name' => 'My report', 'source' => users::class]);
+        $report = $generator->create_report(['name' => 'My report', 'source' => users::class, 'default' => false]);
         $generator->create_condition(['reportid' => $report->get('id'), 'uniqueidentifier' => 'user:fullname']);
 
         $instance = manager::get_report_from_persistent($report);
diff --git a/reportbuilder/tests/external/filters/delete_test.php b/reportbuilder/tests/external/filters/delete_test.php
index 249270592b6..ec51832bf02 100644
--- a/reportbuilder/tests/external/filters/delete_test.php
+++ b/reportbuilder/tests/external/filters/delete_test.php
@@ -85,7 +85,7 @@ class delete_test extends externallib_advanced_testcase {
         /** @var core_reportbuilder_generator $generator */
         $generator = $this->getDataGenerator()->get_plugin_generator('core_reportbuilder');
 
-        $report = $generator->create_report(['name' => 'My report', 'source' => users::class]);
+        $report = $generator->create_report(['name' => 'My report', 'source' => users::class, 'default' => false]);
         $filter = $generator->create_filter(['reportid' => $report->get('id'), 'uniqueidentifier' => 'user:email']);
 
         $user = $this->getDataGenerator()->create_user();
diff --git a/reportbuilder/tests/external/filters/reorder_test.php b/reportbuilder/tests/external/filters/reorder_test.php
index faa60a308de..a05c52dd2c3 100644
--- a/reportbuilder/tests/external/filters/reorder_test.php
+++ b/reportbuilder/tests/external/filters/reorder_test.php
@@ -95,7 +95,7 @@ class reorder_test extends externallib_advanced_testcase {
         /** @var core_reportbuilder_generator $generator */
         $generator = $this->getDataGenerator()->get_plugin_generator('core_reportbuilder');
 
-        $report = $generator->create_report(['name' => 'My report', 'source' => users::class]);
+        $report = $generator->create_report(['name' => 'My report', 'source' => users::class, 'default' => false]);
         $filter = $generator->create_filter(['reportid' => $report->get('id'), 'uniqueidentifier' => 'user:email']);
 
         $user = $this->getDataGenerator()->create_user();
diff --git a/reportbuilder/tests/local/helpers/report_test.php b/reportbuilder/tests/local/helpers/report_test.php
index 8bc6fd34335..1eceae0f5ce 100644
--- a/reportbuilder/tests/local/helpers/report_test.php
+++ b/reportbuilder/tests/local/helpers/report_test.php
@@ -386,6 +386,25 @@ class report_test extends advanced_testcase {
         report::add_report_condition($report->get('id'), 'user:invalid');
     }
 
+    /**
+     * Test adding duplicate report condition
+     */
+    public function test_add_report_condition_duplicate(): void {
+        $this->resetAfterTest();
+        $this->setAdminUser();
+
+        /** @var core_reportbuilder_generator $generator */
+        $generator = $this->getDataGenerator()->get_plugin_generator('core_reportbuilder');
+        $report = $generator->create_report(['name' => 'My report', 'source' => users::class, 'default' => false]);
+
+        // First one is fine.
+        report::add_report_condition($report->get('id'), 'user:email');
+
+        $this->expectException(invalid_parameter_exception::class);
+        $this->expectExceptionMessage('Duplicate condition');
+        report::add_report_condition($report->get('id'), 'user:email');
+    }
+
     /**
      * Test deleting report condition
      */
@@ -536,6 +555,25 @@ class report_test extends advanced_testcase {
         report::add_report_filter($report->get('id'), 'user:invalid');
     }
 
+    /**
+     * Test adding duplicate report filter
+     */
+    public function test_add_report_filter_duplicate(): void {
+        $this->resetAfterTest();
+        $this->setAdminUser();
+
+        /** @var core_reportbuilder_generator $generator */
+        $generator = $this->getDataGenerator()->get_plugin_generator('core_reportbuilder');
+        $report = $generator->create_report(['name' => 'My report', 'source' => users::class, 'default' => false]);
+
+        // First one is fine.
+        report::add_report_filter($report->get('id'), 'user:email');
+
+        $this->expectException(invalid_parameter_exception::class);
+        $this->expectExceptionMessage('Duplicate filter');
+        report::add_report_filter($report->get('id'), 'user:email');
+    }
+
     /**
      * Test deleting report filter
      */
diff --git a/reportbuilder/tests/task/send_schedule_test.php b/reportbuilder/tests/task/send_schedule_test.php
index 7597244733b..7f53bd7ea00 100644
--- a/reportbuilder/tests/task/send_schedule_test.php
+++ b/reportbuilder/tests/task/send_schedule_test.php
@@ -157,9 +157,11 @@ class send_schedule_test extends advanced_testcase {
         $generator = $this->getDataGenerator()->get_plugin_generator('core_reportbuilder');
 
         // Create a report that won't return any data.
-        $report = $generator->create_report(['name' => 'Myself', 'source' => users::class]);
+        $report = $generator->create_report(['name' => 'Myself', 'source' => users::class, 'default' => false]);
 
+        $generator->create_column(['reportid' => $report->get('id'), 'uniqueidentifier' => 'user:username']);
         $generator->create_condition(['reportid' => $report->get('id'), 'uniqueidentifier' => 'user:username']);
+
         manager::get_report_from_persistent($report)->set_condition_values([
             'user:username_operator' => text::IS_EQUAL_TO,
             'user:username_value' => 'baconlettucetomato',
diff --git a/reportbuilder/upgrade.txt b/reportbuilder/upgrade.txt
index cc7be4cb625..6df9844f42c 100644
--- a/reportbuilder/upgrade.txt
+++ b/reportbuilder/upgrade.txt
@@ -28,6 +28,8 @@ Information provided here is intended especially for developers.
 * If a non-default column is specified in a datasource `get_default_column_sorting` method, a coding exception will be thrown
 * Trying to add/annotate duplicate entity names to a report will now throw a coding exception
 * The `get_default_entity_name` method of the base entity class is now private, and shouldn't be overridden in extending classes
+* The report helper methods `add_report_[condition|filter]` now throw an exception when trying to add duplicate conditions or
+  filters to a report
 * Two new methods:
   - `get_default_no_results_notice` and
   - `set_default_no_results_notice`
diff --git a/version.php b/version.php
index cea96a68c54..130f453921b 100644
--- a/version.php
+++ b/version.php
@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2023082200.03;              // YYYYMMDD      = weekly release date of this DEV branch.
+$version  = 2023082200.04;              // YYYYMMDD      = weekly release date of this DEV branch.
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.
 $release  = '4.3dev+ (Build: 20230822)'; // Human-friendly version name