Upgrade whent wrong

After trying to use the file upgrade.php i got the error:

There were a number of issues: Duplicate column name 'time_created'

QUERY: ALTER TABLE `elgg_entity_relationships` ADD COLUMN `time_created` int(11) NOT NULL AFTER `guid_two`;;

The old version was 1.7.6, the new 1.8.1

Please help me out, what to do?