Closed dragonexpert closed 10 years ago
MyFacebook Connect includes an email check. If the user's email is already registered in your database, it links his Facebook ID with the matched user and logins him instead of registering, so there is no way MFC can register an user if his email is already there.
Even if multiple registrations for the same email address is disabled, they can still register using Facebook Connect if their Facebook has the same email.
Link to thread: http://community.mybb.com/thread-157035.html