Validation on IE7

[eluser]taewoo[/eluser]
Hi everyone.

I have a form with custom validation. Basically, it makes sure that the name of a group is unique by looking up the name before trying to insert the record (via "callback_XYZ" feature of CI validation). On FF3, it works fine.. but in IE7, it looks like the form is submitting TWICE (with single form submit "click") b/c the record is added on the DB (i made sure the table is empty) and validation comes back saying that the name is taken.

From this my only guess is that IE7 is somehow submitting twice.
IS there a solution to this? It's making me pull my hair out! :/