To try and clarify:
Unless you are talking about some of the newer tv's that actually have a direct tv tuner built in, there is no difference between hooking up tv's to direct tv or dish network.
You can hook up multiple tv's to one single tuner receiver, no problem. They'll just have to all watch the same channel.
If you don't want them to watch the same channel, then you either need another receiver, or you need the dual tuner/dual output units (Dish 322 or 522).