Bids on homes are not first come first serve. Even if multiple offers were presented, the bank is going to consider them and accept the best one. So unless an offer has been formally accepted and a purchase agreement fully executed feel free to submit an offer. Even if an offer has been accepted a number of things can happen to kill the deal so you may get the home.

Just don't fall in love with a short sale. Often things go sideways and you just need to be patient in your home search and sooner or later you'll get the right home