When you import contacts in Contacts, if any cards are duplicates of existing cards, you can review the duplicates and decide to keep the old card, keep the new card, keep both cards, or merge the cards.
Import contacts.
Accept or review duplicate cards.
Automatically accept duplicates: 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 there are other duplicates, accept or review them.
Resolve all duplicates the same way: Select Apply to All.
Review each duplicate: Click Next.
Click Import.