Rashi writes in Chulin Daf 106a that
בשר חזיר חמור מנבלה דאית ביה תרי איסורי
(Eating) pig meat is worse than (eating meat of) a nevelah (an animal that wasn't slaughtered properly), since there are two prohibitions (when it comes to eating the pig meat, whereas eating nevelah is only one prohibition).
What two prohibitions are there? Why is this worse?