Hi kim standley,
Thanks for using Apple Support Communities. I would first try resetting SyncServices as described here:
If the issue persists after that, I'd move on to this article:
Thank you ariel!!!
I've had similar problems to those of kim for almost a year now. Many events would duplicate and/or repeat in iCal on iPhone (3, 4, & 5!!) even though they didn't repeat in iCal on MacBook Pro. Following your advice the first link didn't work but the third one did! Beautiful - I'm excited to use my mobile iCal the way it was designed to be used.