There is a solution avaliable already, the Edirol V440 have and aditional hardware expansion that lets you split one HD 1080p wide screen video signal in 2 video outputs similar results like the DualHead2Go but with lower resolution output.
This tool is call V-44SW, and it can be used also as a complete independent video mixer
Another (expensive) way is connect wih MIDI 2 V-44SW (Slave mode) to one master V-440 mixer (master controller) you can mix 2 independet TH2G systems. (Imagine the price of this system
http://www.edirol.com/index.php/en/prod ... 386/v-44sw
I also remember that Kramer Electronics has a HD video switcher that do this kind of 2 output split video image.
Fry: imagine my setup without that soda machine? I will feel incomplete..LOL