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If the same contact appears more than once in your phone's address book, you can merge identical contacts so that they will appear only once.
1. Find "Merge contacts"
Slide your finger upwards on the screen.
Press the menu icon.
Press Manage contacts.
Press Merge contacts.
2. Merge identical contacts
Press the field next to the required number.
3. Return to the home screen
Press the Home key to return to the home screen.