I followed the instructions for upgrading (to the latest version of membership and affiliates suites), but when I ran update.php I got this message:

user warning: Duplicate column name 'date' query: ALTER TABLE ms_affiliates_genealogy ADD `date` INT DEFAULT NULL in /home/sciencet/public_html/develop/includes/database.mysql-common.inc on line 298.

And:

The following queries were executed
ms_membership module
Update #6600
No queries
ms_affiliates module
Update #6200
Failed: ALTER TABLE {ms_affiliates_genealogy} ADD `date` INT DEFAULT NULL
ALTER TABLE {ms_affiliates_genealogy} CHANGE `date` `date` INT NOT NULL
Update #6300
ALTER TABLE {ms_affiliates_history} ADD `oid` INT NOT NULL DEFAULT 0

Any insight into why this happened?