Index: includes/functions_user.php
===================================================================
--- includes/functions_user.php	(revision 9713)
+++ includes/functions_user.php	(working copy)
@@ -1016,7 +1016,17 @@
 		}
 		while ($row = $db->sql_fetchrow($result));
 
-		$banlist_ary = array_unique(array_diff($banlist_ary, $banlist_ary_tmp));
+		$banlist_ary_tmp = array_intersect($banlist_ary, $banlist_ary_tmp);
+		
+		if(sizeof($banlist_ary_tmp))
+		{
+			//one or more entities are already banned - delete the existing bans, so they can be re-inserted with the given new length
+			$sql = 'DELETE FROM ' . BANLIST_TABLE . '
+				WHERE ' . $db->sql_in_set($type, $banlist_ary_tmp) . '
+					AND ban_exclude = ' . (int) $ban_exclude;
+			$db->sql_query($sql);
+		}
+		
 		unset($banlist_ary_tmp);
 	}
 	$db->sql_freeresult($result);