When the People web service finds two contacts with the same first and last name, it will link them so they appear as a single contact in your list. You can also link them using “Clean up contacts,” search and link them manually, and unlink contacts.
Link contacts with “Clean up contacts”
If you have two contacts for the same person under different names, you can link these contacts.
In People, click Manage, then click Clean up contacts.
Click Show details for one of the contact sets.
Clear the check box next to any contact in the set you don’t want to link.
Repeat steps 2 and 3 for each contact set.
Click Save and continue.
Search and link manually
You can also link contacts by searching and linking them manually.
In the search field, type the name of the contact you’re looking for.
In the search result, select the contacts you want to link.
Click Link.
Unlink contacts
If two or more contacts have been incorrectly linked, you can unlink them.
In People, select the contact.
Click Links.
Click the X next to any contact you want to unlink.