If you set up iCloud Contacts on your Mac or PC and then see duplicate contacts, follow these steps.
If you see duplicates in Contacts on iCloud.com, visit Apple Support for help.
If you see duplicate contacts only on your computer and not on iCloud.com, follow the steps below.
Follow the steps for your operating system.
Open Contacts.
From the Card menu, select Card > Look for Duplicates.
When asked, click Merge.
Repeat steps 2 and 3 until no duplicates are found.
Visit these Microsoft articles for help: