Buying short sells with 2 Lenders?

My boyfriend and I got accepted the offer to buy a condo in Southern California. The listing price was $150,000 and we offered exactly at asking price. I heard short sells take long time to get approve from the lender, not to mention there are 2 lenders involved. This is our first time and not sure how this is work. Do we have to pay the second lender or $150,000 would be final that we would pay assuming both lenders would approve.