Contact Cleaner is a program for your Windows Mobile 5.0+ phone that helps you remove duplicate and redundant contacts.

Ever get a new phone, sync it to your existing Exchange account, and end up with hundreds of duplicate contacts? Accidentally create a duplicate contact but with different information, and then need to figure out which one to keep and which one to delete? This program is for you!

http://forum.xda-developers.com/showthread.php?t=523893