--- apps/polls/lib/Db/TableManager.php	2023-06-21 12:38:02.300193982 +0200
+++ apps/polls/lib/Db/TableManager-patched.php	2023-06-21 12:48:45.144957659 +0200
@@ -312,12 +312,18 @@
 		if ($this->schema->hasTable($this->dbPrefix . $table)) {
 			// identify duplicates
 			$selection = $qb->selectDistinct('t1.id')
-				->from($table, 't1')
-				->innerJoin('t1', $table, 't2')
-				->where($qb->expr()->lt('t1.id', 't2.id'));
+			->from($table, 't1')
+			->innerJoin('t1', $table, 't2', $qb->expr()->lt('t1.id', 't2.id'));
+
+			$i = 0;
 
 			foreach ($columns as $column) {
-				$selection->andWhere($qb->expr()->eq('t1.' . $column, 't2.' . $column));
+				if ($i > 0) {
+					$selection->andWhere($qb->expr()->eq('t1.' . $column, 't2.' . $column));
+				} else {
+					$selection->where($qb->expr()->eq('t1.' . $column, 't2.' . $column));
+				}
+				$i++;
 			}
 
 			$duplicates = $qb->executeQuery()->fetchAll(PDO::FETCH_COLUMN);