Double penetration means, more then one cock up the ass and the vagina. In this category, it just means that the holes will be filled up with things, cocks the least. You will find bottles placed inside the vaginas and a fist up the ass. It can be even a monster dildo up the ass and a fuck machine in the pussy, it all depends on what mood the sluts were when they were doing the video. Double fisting is yet another type of video that you might find but all in all, both of the holes will be plugged up.