Resolve duplicates while importing contacts into Contacts on Mac
When you import contacts, Contacts displays a message if it finds duplicates of existing contact cards. You can review the duplicates and decide how to handle them.
In the Contacts app on your Mac, when you see the message that duplicate cards have been found, choose what to do:
Accept duplicates without reviewing: Click Import.
Review duplicates and resolve discrepancies: Click Review Duplicate(s) and continue to the next step.
Review the first duplicate by clicking the buttons above the card, then click the button with the option you want.
Keep Old: Keep the old card, and discard the new one (the one you’re importing).
Keep New: Keep the new card and discard the old one.
Keep Both: Keep both cards.
Update: Create an updated card that merges information from both cards.
If that was the only duplicate, click Import. If there are more duplicates, do one of the following:
Resolve all duplicates the same way: Select Apply to All, then click Import.
Review each duplicate: Click Next. When you’ve finished reviewing duplicates, click Import.