I am wanting to see if there is a software program available that will allow me to control two USB-based web cams at the same time from a single computer.
For each, you'll probably need to read the documentation on how to access the numerous webcams.
A google search will for multiple webcams will probably turn up surveillance software... like the shareware http://www.supervisioncam.com/ . You'll have to dig a little deeper to find freeware... or else write your own with (say) tools like the above.
One project I was playing with was using two webcams to produce red-green stereoimages in near real-time... to get a crude 3D webcam. A related use is to try to determine locations from two webcam images...for experimenting with machine vision.
I'm not sure if either is what the OP is doing with two webcams.