The Contacts app uses an intelligent merge feature to combine contact info from various sources (GmailTM, Microsoft® Exchange, Facebook®, new entries, etc.). If contact info was joined in error it can be separated back into individual contacts.
From a Home screen, navigate: Apps > Contacts .
Tap the Menu icon (located in the upper-right).
Tap Manage Contacts then tap Join contacts.
From the Join Suggestion tab, tap a contact to join.
Selected when a check mark is present.