In the People hub in Windows Phone 7, you might have two or more versions of one contact if you have connected to multiple social networks or email accounts. Windows Phone 7 offers you to links multiple contacts. You can link multiple contacts so all their information is displayed in one contact card. In most cases, your phone will do this automatically. For the rest, you can link them manually.
To start linking a contact, select the contact first and at the bottom you can see an link button.
In the linking page, select “Choose a contact” and select the contact you want to link to this.
Once added, you can see both the contacts linked, you can link multiple contacts into one.
When you link two or more contact cards that have different profile pictures or names, you can choose which picture and name will represent the contact.