I can't get rid of duplicated contacts.

Question

I don't know how, but I have duplicated my contacts list. I have gone through and manually deleted the duplicates on a few occasions and don't fancy doing it again. I've tried replacing the contact list on my phone with the contacts in my computer. They are not duplicated. That didn't work.
So, does anyone out there know how to delete the contact from my phone and replace them with the contact from the computer? The only way I've tried is using the advanced sync options under the info tab.
Help will be appreciated.
Sean

Answer 1

I'm assuming here you're not using mobileme, correct? If so, we're gonna have to get serious here, do the following:
Close itunes. Open Address Book and choose Back up Address Book from the File menu. A dialog appears, asking you to choose a save location, chose your DESKTOP—it also adds the current date to the saved file name too. Choose where you want to save the backup, then click Save.
Delete ALL of your contacts in Address Book.
Close Address Book.
Launch isync again & reset sync history.
Reboot your computer.
Launch itunes, & under preferences, disable auto sync when an ipod/iphone is connected.
Connect your phone, DO NOT SYNC, at this point.
Right click the phone in the device pane & select "reset warnings".
Go ahead & sync your phone now, you should get a warning regarding your contacts, asking to merge or replace, select REPLACE.
When finished, verify that ALL contacts have been removed from your phone.
Unmount your phone & close itunes.
Launch Address Book, in Address Book, choose Revert to Address Book Backup from the File menu. In the resulting dialog, locate your backup file(it's on your desktop & it ends with a .abbu extension), select it, and click Open.
Verify that all your contacts are back in Address Book.
Close Address Book.
Put one contact on your phone, it can be fake, doesn't matter.
Launch itunes, connect your phone, right click again & select "reset warnings".
Sync your phone, you should get another popup regarding your contacts, asking to merge or replace, select MERGE this time.
Hopefully, your duplicate contact problem should be fixed.