"Will the final bid be the higher of the two limits used by the snipers?"
The sniper who bids the most will win. The amount will be the amount of the lower of the two bids PLUS whatever the bid increment is for that level.

"When are the sniped bids recognized? (i.e. how close to auction close are they submitted)"
They're submitted at the point the sniper has them programmed for

"And wouldn't the final bid sometimes get out of hand because of two snipers?"
Only if 2 snipers have put unreasonably high amounts into the snipe programs. The same thing happens when 2 bidders get into a bidding war.