Ended up with duplicate contact entries due to active sync? Yes, me too. I ended up with three entries per person on my phone which was exciting. Despite the excitement I decided it was time to resolve. Fire up Outlook and arrange your contacts by "date created". You will find all the duplicates were created on a specific date. In my case I had two days in which all my contacts were duplicated. Select the duplications, hit the delete key and then resync your phone, this should remove all the duplicate entries off your phone without and need for 3rd party software.

Cheers
Ryan Partington