repeating same contacts

On my iPhone 4 somehow I get multiple phone contacts in my directory. I keep deleting duplicates and they re-appear. Where is it coming from. I have a imac and a powerbook w/ idisk. How do I clear them and stop them from coming back clear them out.

It's not Google

I believe it's on mobile me, in some cases I have 8-10 of same contact w phone #s or shared with nothing else