No, you can only get one FP at a time. Once you get it, you can't get another one for an hour (unless it has changed to two hours now?).
When you look at the FP, it's going to show you the time window that you can go back to the ride and walk on it. It will also show you what time you are eligible to get another FP.
So, say you get a FP for Space Mountain at the MK at 10AM. The FP is good to return between 12:30 and 1:30. Also on the pass it would say that you could get another FP at 11AM. This means that even though you have yet to use your Space Mountain FP you can go and get a FP for Splash Mountain at 11AM.
Make sense? It's a lot more simple than it sounds.
Craig