diff --git a/classes/GroupReduction.php b/classes/GroupReduction.php
index ba21a6694..599342844 100644
--- a/classes/GroupReduction.php
+++ b/classes/GroupReduction.php
@@ -216,13 +216,18 @@ class GroupReductionCore extends ObjectModel
 			FROM `'._DB_PREFIX_.'product_group_reduction_cache` pgr
 			WHERE pgr.`id_product` = '.(int)$id_product_old
 		);
+
 		if (!$res)
 			return true;
+
+		$query = '';
+
 		foreach ($res as $row)
 		{
-			$query = 'INSERT INTO `'._DB_PREFIX_.'product_group_reduction_cache` (`id_product`, `id_group`, `reduction`) VALUES ';
-			$query .= '('.(int)$id_product.', '.(int)$row['id_group'].', '.(float)$row['reduction'].')';
+			$query .= 'INSERT INTO `'._DB_PREFIX_.'product_group_reduction_cache` (`id_product`, `id_group`, `reduction`) VALUES ';
+			$query .= '('.(int)$id_product.', '.(int)$row['id_group'].', '.(float)$row['reduction'].') ON DUPLICATE KEY UPDATE `reduction` = '.(float)$row['reduction'].';';
 		}
+
 		return Db::getInstance()->execute($query);
 	}