User name, Email address, and facebook accounts all different?

[Huskerarob]

When i first signed up for spotify, i noticed that if you log in under your e-mail, as apposed to your user name, you would have 2 seperate accounts for the same person.  So my XXXXXX@gmail.com would be empty, when I log into Huskerarob account (username, but both same accounts) this login name would have my playlists.

So facebook was added, and i intergrated.  When I login thru facebook, and my username the playlists are the same.  One difference now though.  I have different subscribers for facebook, and when i login through my username (same playlist) i have different subscribers on the SAME playlists.  Why are they seperate?  Is this a bug?  I could not find anything on this.

[Stupify]

If you log in "under your email", you log in using Facebook. You may be confused here if you have the same password on both your Spotify username account and your Facebook account.

Basically, if you type an email in the username field, you log in using Facebook. If you type anything else, you log in using a Spotify username.