The multi-map demo support is not necessarily fully functional, so it's better to keep different maps as separate demos (plus it makes the demos easier to watch). I mainly added this because somebody had a recording of a cheater that was on the second map of the demo. Even then, I couldn't get it to work, because there was a map download between maps. There are probably a lot of things that break it. I'm surprised I got it working at all. It doesn't seem very high priority, so I probably won't work on it much more, if at all.