diff --git a/lib/completionlib.php b/lib/completionlib.php
index 77c34bad9cf..94a9271327b 100644
--- a/lib/completionlib.php
+++ b/lib/completionlib.php
@@ -1024,6 +1024,20 @@ class completion_info {
             $userid = $USER->id;
         }
 
+        // Some call completion_info::get_data and pass $cm as an object with ID only. Make sure course is set as well.
+        if ($cm instanceof stdClass && !isset($cm->course)) {
+            $cm->course = $this->course_id;
+        }
+        // Make sure we're working on a cm_info object.
+        $cminfo = cm_info::create($cm, $userid);
+
+        // Create an anonymous function to remove the 'other_cm_completion_data_fetched' key.
+        $returnfilteredvalue = function(array $value): stdClass {
+            return (object) array_filter($value, function(string $key): bool {
+                return $key !== 'other_cm_completion_data_fetched';
+            }, ARRAY_FILTER_USE_KEY);
+        };
+
         // See if requested data is present in cache (use cache for current user only).
         $usecache = $userid == $USER->id;
         $cacheddata = array();
@@ -1036,19 +1050,22 @@ class completion_info {
                 if ($cacheddata['cacherev'] != $this->course->cacherev) {
                     // Course structure has been changed since the last caching, forget the cache.
                     $cacheddata = array();
-                } else if (isset($cacheddata[$cm->id])) {
-                    return (object)$cacheddata[$cm->id];
+                } else if (isset($cacheddata[$cminfo->id])) {
+                    $data = (array) $cacheddata[$cminfo->id];
+                    if (empty($data['other_cm_completion_data_fetched'])) {
+                        $data += $this->get_other_cm_completion_data($cminfo, $userid);
+                        $data['other_cm_completion_data_fetched'] = true;
+
+                        // Put in cache.
+                        $cacheddata[$cminfo->id] = $data;
+                        $completioncache->set($key, $cacheddata);
+                    }
+
+                    return $returnfilteredvalue($cacheddata[$cminfo->id]);
                 }
             }
         }
 
-        // Some call completion_info::get_data and pass $cm as an object with ID only. Make sure course is set as well.
-        if ($cm instanceof stdClass && !isset($cm->course)) {
-            $cm->course = $this->course_id;
-        }
-        // Make sure we're working on a cm_info object.
-        $cminfo = cm_info::create($cm, $userid);
-
         // Default data to return when no completion data is found.
         $defaultdata = [
             'id' => 0,
@@ -1086,12 +1103,9 @@ class completion_info {
                     $cacheddata[$data->cmid] = $defaultdata;
                     $cacheddata[$data->cmid]['coursemoduleid'] = $data->cmid;
                 } else {
-                    $cacheddata[$data->cmid] = (array) $data;
+                    unset($data->cmid);
+                    $cacheddata[$data->coursemoduleid] = (array) $data;
                 }
-
-                // Add the other completion data for this user in this module instance.
-                $othercminfo = $cminfos[$data->cmid];
-                $cacheddata[$othercminfo->id] += $this->get_other_cm_completion_data($othercminfo, $userid);
             }
 
             if (!isset($cacheddata[$cminfo->id])) {
@@ -1099,6 +1113,7 @@ class completion_info {
                 $this->internal_systemerror($errormessage);
             }
 
+            $data = $cacheddata[$cminfo->id];
         } else {
             // Get single record
             $data = $DB->get_record('course_modules_completion', array('coursemoduleid' => $cminfo->id, 'userid' => $userid));
@@ -1108,18 +1123,24 @@ class completion_info {
                 // Row not present counts as 'not complete'.
                 $data = $defaultdata;
             }
-            // Fill the other completion data for this user in this module instance.
-            $data += $this->get_other_cm_completion_data($cminfo, $userid);
 
-            // Put in cache
+            // Put in cache.
             $cacheddata[$cminfo->id] = $data;
         }
 
+        // Fill the other completion data for this user in this module instance.
+        $data += $this->get_other_cm_completion_data($cminfo, $userid);
+        $data['other_cm_completion_data_fetched'] = true;
+
+        // Put in cache
+        $cacheddata[$cminfo->id] = $data;
+
         if ($usecache) {
             $cacheddata['cacherev'] = $this->course->cacherev;
             $completioncache->set($key, $cacheddata);
         }
-        return (object)$cacheddata[$cminfo->id];
+
+        return $returnfilteredvalue($cacheddata[$cminfo->id]);
     }
 
     /**
@@ -1240,6 +1261,7 @@ class completion_info {
         $cmcontext = context_module::instance($data->coursemoduleid);
 
         $completioncache = cache::make('core', 'completion');
+        $cachekey = "{$data->userid}_{$cm->course}";
         if ($data->userid == $USER->id) {
             // Fetch other completion data to cache (e.g. require grade completion status, custom completion rule statues).
             $cminfo = cm_info::create($cm, $data->userid); // Make sure we're working on a cm_info object.
@@ -1249,18 +1271,19 @@ class completion_info {
             }
 
             // Update module completion in user's cache.
-            if (!($cachedata = $completioncache->get($data->userid . '_' . $cm->course))
+            if (!($cachedata = $completioncache->get($cachekey))
                     || $cachedata['cacherev'] != $this->course->cacherev) {
                 $cachedata = array('cacherev' => $this->course->cacherev);
             }
-            $cachedata[$cm->id] = $data;
-            $completioncache->set($data->userid . '_' . $cm->course, $cachedata);
+            $cachedata[$cm->id] = (array) $data;
+            $cachedata[$cm->id]['other_cm_completion_data_fetched'] = true;
+            $completioncache->set($cachekey, $cachedata);
 
             // reset modinfo for user (no need to call rebuild_course_cache())
             get_fast_modinfo($cm->course, 0, true);
         } else {
             // Remove another user's completion cache for this course.
-            $completioncache->delete($data->userid . '_' . $cm->course);
+            $completioncache->delete($cachekey);
         }
 
         // For single user actions the code must reevaluate some completion state instantly, see MDL-32103.
diff --git a/lib/tests/completionlib_test.php b/lib/tests/completionlib_test.php
index b393c90dbe8..ecd75696b2f 100644
--- a/lib/tests/completionlib_test.php
+++ b/lib/tests/completionlib_test.php
@@ -89,6 +89,10 @@ class completionlib_test extends advanced_testcase {
     public static function assertEquals($expected, $actual, string $message = '', float $delta = 0, int $maxDepth = 10,
                                         bool $canonicalize = false, bool $ignoreCase = false): void {
         // Nasty cheating hack: prevent random failures on timemodified field.
+        if (is_array($actual) && (is_object($expected) || is_array($expected))) {
+            $actual = (object) $actual;
+            $expected = (object) $expected;
+        }
         if (is_object($expected) and is_object($actual)) {
             if (property_exists($expected, 'timemodified') and property_exists($actual, 'timemodified')) {
                 if ($expected->timemodified + 1 == $actual->timemodified) {
@@ -804,6 +808,70 @@ class completionlib_test extends advanced_testcase {
         }
     }
 
+    /**
+     * @covers ::get_data
+     */
+    public function test_get_data_successive_calls(): void {
+        global $DB;
+
+        $this->setup_data();
+        $this->setUser($this->user);
+
+        $choicegenerator = $this->getDataGenerator()->get_plugin_generator('mod_choice');
+        $choice = $choicegenerator->create_instance([
+            'course' => $this->course->id,
+            'completion' => COMPLETION_TRACKING_AUTOMATIC,
+            'completionview' => true,
+            'completionsubmit' => true,
+        ]);
+
+        $cm = get_coursemodule_from_instance('choice', $choice->id);
+
+        // Let's manually create a course completion record instead of going through the hoops to complete an activity.
+        $cmcompletionrecord = (object) [
+            'coursemoduleid' => $cm->id,
+            'userid' => $this->user->id,
+            'completionstate' => COMPLETION_NOT_VIEWED,
+            'viewed' => 0,
+            'overrideby' => null,
+            'timemodified' => 0,
+        ];
+        $DB->insert_record('course_modules_completion', $cmcompletionrecord);
+
+        // Mock other completion data.
+        $completioninfo = new completion_info($this->course);
+
+        $modinfo = get_fast_modinfo($this->course);
+        $results = [];
+        foreach ($modinfo->cms as $testcm) {
+            $result = $completioninfo->get_data($testcm, true);
+            $this->assertTrue(property_exists($result, 'id'));
+            $this->assertTrue(property_exists($result, 'coursemoduleid'));
+            $this->assertTrue(property_exists($result, 'userid'));
+            $this->assertTrue(property_exists($result, 'completionstate'));
+            $this->assertTrue(property_exists($result, 'viewed'));
+            $this->assertTrue(property_exists($result, 'overrideby'));
+            $this->assertTrue(property_exists($result, 'timemodified'));
+            $this->assertFalse(property_exists($result, 'other_cm_completion_data_fetched'));
+
+            $this->assertEquals($testcm->id, $result->coursemoduleid);
+            $this->assertEquals($this->user->id, $result->userid);
+            $this->assertEquals(0, $result->viewed);
+
+            $results[$testcm->id] = $result;
+        }
+
+        $result = $completioninfo->get_data($cm);
+        $this->assertTrue(property_exists($result, 'customcompletion'));
+
+        // The data should match when fetching modules individually.
+        (cache::make('core', 'completion'))->purge();
+        foreach ($modinfo->cms as $testcm) {
+            $result = $completioninfo->get_data($testcm, false);
+            $this->assertEquals($result, $results[$testcm->id]);
+        }
+    }
+
     /**
      * Tests for completion_info::get_other_cm_completion_data().
      *
@@ -909,8 +977,15 @@ class completionlib_test extends advanced_testcase {
         $this->assertEquals($d1, $data->id);
         $cache = cache::make('core', 'completion');
         // Cache was not set for another user.
-        $this->assertEquals(array('cacherev' => $this->course->cacherev, $cm->id => $data),
-            $cache->get($data->userid . '_' . $cm->course));
+        $cachevalue = $cache->get("{$data->userid}_{$cm->course}");
+        $this->assertEquals([
+            'cacherev' => $this->course->cacherev,
+            $cm->id => array_merge(
+                (array) $data,
+                ['other_cm_completion_data_fetched' => true]
+            ),
+        ],
+        $cachevalue);
 
         // 2) Test with existing data and for different user.
         $forum2 = $this->getDataGenerator()->create_module('forum', array('course' => $this->course->id), $completionauto);
@@ -928,7 +1003,11 @@ class completionlib_test extends advanced_testcase {
         $c->internal_set_data($cm2, $d2);
         // Cache for current user returns the data.
         $cachevalue = $cache->get($data->userid . '_' . $cm->course);
-        $this->assertEquals($data, $cachevalue[$cm->id]);
+        $this->assertEquals(array_merge(
+            (array) $data,
+            ['other_cm_completion_data_fetched' => true]
+        ), $cachevalue[$cm->id]);
+
         // Cache for another user is not filled.
         $this->assertEquals(false, $cache->get($d2->userid . '_' . $cm2->course));