Don't feel bad - I finished a project today that was scheduled for last Thursday... before the customer came up with THREE "emergencies" that involved things that were "discovered" to be wrong, months after they last said there was a problem, and all needing fixing "now". And, by the way, why isn't that Thursday project done yet?
What I would do at this point would be to write down the information for the created groups, then delete their entries from JUST the groups table. Then re-enter them. This should change NOTHING... but, there is a chance that it will. I would want to avoid outright removal of the groups and their members, if possible, because putting the members back in can be a pain in the rear.
One other thing I'd try is having phpmyadmin dump the data to an SQL file, and look at the file to see if their are any duplicate entries. An editor that can sort files is nice for this.