diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index 200e6157c3c..82bbb335eee 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -6696,6 +6696,34 @@ FROM
         upgrade_main_savepoint(true, 2011070102.08);
     }
 
+    if ($oldversion < 2011070103.04) {
+
+        upgrade_set_timeout(60*20); // This may take a while
+        // MDL-28180. Some missing restrictions in certain backup & restore operations
+        // were causing incorrect duplicates in the course_completion_aggr_methd table.
+        // This upgrade step takes rid of them.
+        $sql = 'SELECT course, criteriatype, MIN(id) AS minid
+                  FROM {course_completion_aggr_methd}
+              GROUP BY course, criteriatype
+                HAVING COUNT(*) > 1';
+        $duprs = $DB->get_recordset_sql($sql);
+        foreach ($duprs as $duprec) {
+            // We need to handle NULLs in criteriatype diferently
+            if (is_null($duprec->criteriatype)) {
+                $where = 'course = ? AND criteriatype IS NULL AND id > ?';
+                $params = array($duprec->course, $duprec->minid);
+            } else {
+                $where = 'course = ? AND criteriatype = ? AND id > ?';
+                $params = array($duprec->course, $duprec->criteriatype, $duprec->minid);
+            }
+            $DB->delete_records_select('course_completion_aggr_methd', $where, $params);
+        }
+        $duprs->close();
+
+        // Main savepoint reached
+        upgrade_main_savepoint(true, 2011070103.04);
+    }
+
     return true;
 }
 
diff --git a/version.php b/version.php
index 81531b05a86..388102c6432 100644
--- a/version.php
+++ b/version.php
@@ -30,7 +30,7 @@
 defined('MOODLE_INTERNAL') || die();
 
 
-$version  = 2011070103.03;              // 20110701      = branching date YYYYMMDD - do not modify!
+$version  = 2011070103.04;              // 20110701      = branching date YYYYMMDD - do not modify!
                                         //         RR    = release increments - 00 in DEV branches
                                         //           .XX = incremental changes