or... go to your PC / open your gmail account / look on far left side and select "contatcs" / look in the big main box, bottom right corner "find duplicates" / click that and then "merge" duplicates
be sure to resync once this is done. on droid (from home screen) menu / setting / accounts & sync / and then select what account to sync and check auto-sync.... which sort of makes me think you might have synced 2 gmail contact lists -- check in the area I just got you to and see if 2 different gmail accounts have contacts synced. If this is confusing, ask for more info.