Hey Ray;
RE: having two identical projectors... You might want to wire in a switch (DPDT) on one of them so you can invert the X signal going to the X amp. Then split the output from your pangolin board and feed the same signal to both projectors, but flip the "invert x" switch on. If you place your projectors on either side of the room, the beams will converge (or diverge), which looks a lot better (to me at least!) than having them move back and fourth in a windshield wiper pattern.
I've seen this done a few times, and it really looks great. (Well, for beam shows anyway.)
Adam