Hello fgeye,
Yes, it's possible, I do that, to broadcast the live stream from two separate computers simultaneously.
You need to set up Broadwave on each to use a different port number. For example, PC1 uses port 8080 and PC2 uses port 8081. (or choose your own port numbers). You then need to set up port forwarding on your router to forward incoming traffic for each of the ports to their respective PCs' internal fixed IP address.
So, from an external PC on the internet, you simply select http:// publicIP : 8080/broadwave.mp3 for one, and http:// publicIP : 8081/broadwave.mp3 for the second one (with no spaces of course, which I added for clarity).
On my router, I had to define two different "custom services" and select a target local fixed IP address for each of them. If you can get one working, then add the other one is an easy step.
Let us know how you get on.