I am considering trying to setup a multiseat system. It seems like this would be pretty straight forward if I had two graphics cards or if I didn't need hardware based OpenGL acceleration. Is it possible to setup a multi seat system with only a single dual-headed graphics card?
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=529043 says no. There is no "clean" solution using only X. However, it is hinted this is possible with X and Xephyr. https://bbs.archlinux.org/viewtopic.php?id=79620 has further information on this, but I didn't try it, so I won't copy the contents as a solution.