The People 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.
Link Contacts
From a Home screen, navigate: Apps > People.
Tap the appropriate contact.
Tap the Menu icon (located in the upper-right).
Tap Link.
Tap Other contacts then select the applicable contact.
Tap DONE.
Unlink Contacts
From a Home screen, navigate: Apps > People.
Tap the Menu icon (located in the upper-right).
Tap Manage contacts.
Tap Linked Contacts.
Tap the Link icon (next to the contact name). Contacts are linked when is present. Contacts are unlinked when is present.