Fall out Boy mixtape?

Okay, I'm so confused about this Fall out Boy mixtape thing. So they released around the same time as their new album. It has demos from new songs on their album and demo songs from other Decaydance bands like Cobra STarship and Panic at the Disco. But one of PATD's songs on there has a different band name called Paul Revere JUmpsuit Apparatus?!! And, can I buy this or download it some where? I am so confused it's not even funny. I need help from some of you big FOB fans, thanks!!