Quadruple contacts on my iPhone 4S

I sync'd the contact of my old iPhone 3G with my yahoo mail contacts. That worked ok for while, then at some point all the the Yahoo contacts were duplicated (every contact appeared twice in my contacts list) on the iPhone. This was annoying, but I could not find a quick fix, so I lived with it.

Yesterday I bought a 4S and set up my various accounts and set up iCloud. Now the phone has 4 copies of my yahoo contacts. I don't know that point during the setup the contacts got duped(again).

Now I want to clean it all up. How?

Edit in response to comment. There are two copies of each contact in the yahoo account.and two copies in the iCloud account. And 4 copies in "all contacts".

You can sign up to google voice and sync with google voice and them go on desk top link onto your gv account and press get rid of duplicates