Two cameras from different angles makes it possible for Torbe/PB to create a more dynamic end product when editing. Primarily in the "best scenes" version, but also the cam1 and cam2 versions can include some sequences from each other. Many of the older PB scenes were edited that way, so when you for example watch the cam2 version (my favorite) of a scene, most of the video is from cam2 especially the cumshots, but some short sequences from cam 1 is also included. This can give more dynamic to the scene even if the primary camera is cam2.
Even if I mostly prefer the cam2 version (Downwards Headshot), I also like to watch the best scenes version for some variation. I think the different version really add some extra value, it's one of the things that makes PB "Premium" to me.