The Philly Roller Girls are currently known as Philly Roller Derby.
A virtually identical patch is already posted for Philly Roller Girls, but a close examination reveals they're not the same thing. The first difference is the color. This is a deeper blue than the other. That could be more a matter of lighting in the photo though. The real proof is in the size of the bell/skate. In this patch it's entirely surrounded by white. In the other patch it's done a bit larger and bleeds significantly into the outer blue ring. This was definitely not a simple error of production. Also, the lace holes are filled in on this design. On the other they're hollow circles.