Contacts table with multiple entries?
user table
---------
USERID
EmailAddress

User Details
-------------
USerDetailID
USERID (FK)
FirstName
-----

USER_Contact_Mapping
--------------------
USERcontactMapID 
UserID
contactID


User table hold info of both User and contact.This table can by utilise to hold other 
info which won't be duplicated.

User Details table hold info of both User and contact.This table contain multiple detail of same user.
Example 

USER_Contact_Mapping contain relation between USERID and ContactID.This table is must.