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 Contacts, select a contact.
Tap Edit (located in the upper-right).
Tap the Menu icon (located in the upper-right).
Tap a contact.
Tap Show all contacts to view additional contacts.