multiple groups of same name in iPhone address book
I just got an iPhone 5 and synced it with my iCloud account. I have groups in my address book and some of them have been replicated in my iPhone 5 twice or thrice. I have an iPad which I also sync with iCloud, and I don't have a problem with the groups in my address book in the iPad. So, I'm wondering why this happened on the iPhone.
Any ideas on why this happened?
iPhone 5, iOS 6.0.2