diff --git a/app/DB.php b/app/DB.php
index 1a3a208e35e..5b1258e5a8e 100644
--- a/app/DB.php
+++ b/app/DB.php
@@ -41,4 +41,21 @@ public static function caseInsensitiveLikeOperator(): string
 
         return 'LIKE';
     }
+
+    /**
+     * @internal
+     */
+    public static function groupConcat(string $column): string
+    {
+        switch (DB::connection()->getDriverName()) {
+            case 'pgsql':
+            case 'sqlsrv':
+                return 'STRING_AGG(' . $column . ", ',')";
+
+            case 'mysql':
+            case 'sqlite':
+            default:
+                return 'GROUP_CONCAT(' . $column . ')';
+        }
+    }
 }
diff --git a/app/Services/AdminService.php b/app/Services/AdminService.php
index 7da328812cd..f4761029a02 100644
--- a/app/Services/AdminService.php
+++ b/app/Services/AdminService.php
@@ -39,10 +39,13 @@
 use League\Flysystem\StorageAttributes;
 
 use function array_map;
+use function array_unique;
 use function explode;
 use function fclose;
 use function fread;
+use function implode;
 use function preg_match;
+use function sort;
 
 /**
  * Utilities for the control panel.
@@ -117,7 +120,7 @@ public function duplicateRecords(Tree $tree): array
             ->where('s_file', '=', $tree->id())
             ->groupBy(['s_name'])
             ->having(new Expression('COUNT(s_id)'), '>', '1')
-            ->select([new Expression('GROUP_CONCAT(s_id) AS xrefs')])
+            ->select([new Expression(DB::groupConcat('s_id') . ' AS xrefs')])
             ->orderBy('xrefs')
             ->pluck('xrefs')
             ->map(static function (string $xrefs) use ($tree): array {
@@ -127,6 +130,14 @@ public function duplicateRecords(Tree $tree): array
             })
             ->all();
 
+        // Database agnostic way to do GROUP_CONCAT(DISTINCT x ORDER BY x)
+        $distinct_order_by = static function (string $xrefs): string {
+            $array = explode(',', $xrefs);
+            sort($array);
+
+            return implode(',', array_unique($array));
+        };
+
         $individuals = DB::table('dates')
             ->join('name', static function (JoinClause $join): void {
                 $join
@@ -137,10 +148,11 @@ public function duplicateRecords(Tree $tree): array
             ->whereIn('d_fact', ['BIRT', 'CHR', 'BAPM', 'DEAT', 'BURI'])
             ->groupBy(['d_year', 'd_month', 'd_day', 'd_type', 'd_fact', 'n_type', 'n_full'])
             ->having(new Expression('COUNT(DISTINCT d_gid)'), '>', '1')
-            ->select([new Expression('GROUP_CONCAT(DISTINCT d_gid ORDER BY d_gid) AS xrefs')])
-            ->distinct()
+            ->select([new Expression(DB::groupConcat('d_gid') . ' AS xrefs')])
             ->orderBy('xrefs')
             ->pluck('xrefs')
+            ->map($distinct_order_by)
+            ->unique()
             ->map(static function (string $xrefs) use ($tree): array {
                 return array_map(static function (string $xref) use ($tree): Individual {
                     return Registry::individualFactory()->make($xref, $tree);
@@ -153,7 +165,7 @@ public function duplicateRecords(Tree $tree): array
             ->groupBy([new Expression('LEAST(f_husb, f_wife)')])
             ->groupBy([new Expression('GREATEST(f_husb, f_wife)')])
             ->having(new Expression('COUNT(f_id)'), '>', '1')
-            ->select([new Expression('GROUP_CONCAT(f_id) AS xrefs')])
+            ->select([new Expression(DB::groupConcat('f_id') . ' AS xrefs')])
             ->orderBy('xrefs')
             ->pluck('xrefs')
             ->map(static function (string $xrefs) use ($tree): array {
@@ -168,7 +180,7 @@ public function duplicateRecords(Tree $tree): array
             ->where('descriptive_title', '<>', '')
             ->groupBy(['descriptive_title'])
             ->having(new Expression('COUNT(DISTINCT m_id)'), '>', '1')
-            ->select([new Expression('GROUP_CONCAT(m_id) AS xrefs')])
+            ->select([new Expression(DB::groupConcat('m_id') .' AS xrefs')])
             ->orderBy('xrefs')
             ->pluck('xrefs')
             ->map(static function (string $xrefs) use ($tree): array {