diff --git a/mod/feedback/classes/completion.php b/mod/feedback/classes/completion.php
index 75096dcf9ea..3477629d047 100644
--- a/mod/feedback/classes/completion.php
+++ b/mod/feedback/classes/completion.php
@@ -517,7 +517,7 @@ class mod_feedback_completion extends mod_feedback_structure {
      */
     protected function find_last_completed() {
         global $USER, $DB;
-        if (isloggedin() || isguestuser()) {
+        if (!isloggedin() || isguestuser()) {
             // Not possible to retrieve completed feedback for guests.
             return false;
         }
diff --git a/mod/feedback/db/upgrade.php b/mod/feedback/db/upgrade.php
index 2e1644ecc38..7455297d9d6 100644
--- a/mod/feedback/db/upgrade.php
+++ b/mod/feedback/db/upgrade.php
@@ -146,5 +146,31 @@ function xmldb_feedback_upgrade($oldversion) {
     // Moodle v3.1.0 release upgrade line.
     // Put any upgrade step following this.
 
+    if ($oldversion < 2016052301) {
+
+        // Delete duplicated records in feedback_completed. We just keep the last record of completion.
+        // Related values in feedback_value won't be deleted (they won't be used and can be kept there as a backup).
+        $sql = "SELECT MAX(id) as maxid, userid, feedback, courseid
+                  FROM {feedback_completed}
+                 WHERE userid <> 0
+              GROUP BY userid, feedback, courseid
+                HAVING COUNT(id) > 1";
+
+        if ($duplicatedrows = $DB->get_recordset_sql($sql)) {
+            foreach ($duplicatedrows as $row) {
+                $DB->delete_records_select('feedback_completed', 'userid = ? AND feedback = ? AND courseid = ? AND id <> ?', array(
+                    $row->userid,
+                    $row->feedback,
+                    $row->courseid,
+                    $row->maxid,
+                ));
+            }
+        }
+        $duplicatedrows->close();
+
+        // Feedback savepoint reached.
+        upgrade_mod_savepoint(true, 2016052301, 'feedback');
+    }
+
     return true;
 }
diff --git a/mod/feedback/version.php b/mod/feedback/version.php
index 5e98b6bd07f..7249ddc10eb 100644
--- a/mod/feedback/version.php
+++ b/mod/feedback/version.php
@@ -24,7 +24,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version   = 2016052300;       // The current module version (Date: YYYYMMDDXX)
+$plugin->version   = 2016052301;       // The current module version (Date: YYYYMMDDXX)
 $plugin->requires  = 2016051900;    // Requires this Moodle version
 $plugin->component = 'mod_feedback';   // Full name of the plugin (used for diagnostics)
 $plugin->cron      = 0;