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 a contact to link.
Tap the Menu icon (located in the upper-right).
Tap a contact.
If the applicable contact is not under the 'Suggested contacts' section, tap Show all contacts.