Remove duplicates from your Mac
Apple's Address Book (OS X Lion) and Contacts (OS X Mountain Lion) apps both have the ability to scan and remove duplicate contacts by merging them together.
This tool can also remove duplicates from Outlook for Mac if you've enable the sync between Outlook for Mac and the Apple Contacts app.
- Open Address Book or Contacts (depending on your OS version)
- Select "Card" from the menu bar
- Select "Look for Duplicates..."
- See "X cards containing duplicate information was found"
- Select "Merge"
All duplicate contacts should be removed and should now be merged.