I just noticed today while trying to walk a friend through how to use my site that the Login with Facebook button did not do what I expected.
Here is the situation.
The friend already created an account on my site days ago using the Register with Facebook button. Today we tried the site from a different PC and when we clicked the login with facebook button the site errored saying "A user with this username already exists" as if it were trying to run the register routine.
Is this expected?