[Dan Waxman]

If I recall correctly, the USBCamera class is implemented as a singleton, and as a result you can't use two cameras in any intuitive way. There's a chance I'm wrong on that, but I recall my team messing around with it and looking at the source code and I believe that was the takeaway. I remember there was a hacky way here on CD not too long ago though. I found it easier to just use an IP Camera and USB camera instead of two USBs, but I'm pretty sure there is a way.