Ticket #11465: 11465.3.diff

src/wp-admin/includes/post.php

@@ -819 +819 @@
 
                 $metakey = wp_slash( $metakey );
 
-                return add_post_meta( $post_ID, $metakey, $metavalue );
+                return update_post_meta( $post_ID, $metakey, $metavalue );
         }
 
         return false;