In addition, the home seller may decide to sue the buyer and ask the judge to force them to perform according to the contract. The judge may judge in their favor with monetary damages. This is why I don't recommend putting multiple offers on different short sales. It puts the home sellers at risk of losing their home to foreclosure as a result of a buyer wasting their time on a short sale.
If you are buying, then make sure the seller's agent is experienced at short sales and has a good track record of short sale success. If you are selling, then I would recommend accepting offers from only buyers that are truly interested in buying your home. Ask them to commit to waiting for an answer on the short sale. The short sale process is much simpler when a buyer commits to buy a certain home if the short sale is approved. They get the home they want and the short sale only has to be approved one time.