is it ok to peel paper from faced fiberglass batt insulation?
You're asking two questions:

Is it ok?
Yes, it's ok. There's no substantial difference between the resulting fiberglass batt and a new, unfaced batt aside from marginally less fiberglass due to what pulls off with the paper. The batts may want to pull out as you remove the paper, so it might make sense to simply do it on the floor and reinstall backward so you have a cleaner face exposed to the room. 

Is it necessary?
Your plan is sound: Don't have more than one vapor barrier.