No, multiple firmware installations do not exist. This is not support by either VTS or GEMS currently. That is, you can not have a 1.93 and 1.94 in one place, nor will 1.94 and 2.0. You can of course mix and match putch releases (1.94r and 1.94s etc).
I think though, that everyone is missing the point on this thread. Steve (as I understand it) was asking if he could run visible light along with inferred in the same election. The answer to this question is yes, because 2.0 will support both VL and IR. They will, however, have to upgrade all their machines to 2.0.