I presume you're talking about live TV, and if so, the answer is: Absolutely.
Each place you want to watch TV requires access to its own tuner. How many tuners do you have? That's how many live TV instances you can have going. They can each be whatever channel you want--all different channels, all the same channel, or anything in between.
Of course, if a tuner is needed for a scheduled recording, you'll want to let it have that. In fact, most people don't watch live TV; most watch recorded TV. You can watch recorded TV anywhere, while the main PC is busy using the tuners to record new stuff.