While it is possible to get too much 02, it's not possible to do it with regular at home 02 sources. The most you can get with most at home concentrators or reservoirs for liquid, is 15 LPM, and chances are good that wouldn't do it. In the hospital you can certainly get too much; they can produce a good deal more.

Your bi-pap machine doesn't produce 02; it provides pressure helping your inhale and your exhale. You can hook your 02 into the bi-pap, but unless you are adding in more than 15LPM from some source, you don't run any risk of getting too much 02.