When you have two or more entries for the same contact, you can join them into a single entry. You can also separate contacts that were joined.
Open the Contacts app, then tap the Menu Key .
Tap Join contacts.
Select a tab at the top of the screen.
Tap Join suggestion to select entries to merge.
Tap Joined contacts to select entries to separate.
Checkmark the entry (or entries) you want, then tap Join or Separate.