On one particular short sale one of the Realtors with my brokerage and I have been working with two seperate short sale or loss mitigation departments from one of the largest lenders.  

At first both invesors were holding out for a deficiency. Eventually we broker the second down.  But the lender wanted us to close in two weeks.  We were still negotiating with the first. We suggest a short payoff.  They agreed but tried to condition their short pay on the eventual short sale of the property with the first lender.  

My Realtor suggested that might be a violation of RESPA, I thought it would be contractally impossible.  (Were they going to return the money if the first did not accept our terms.)

In the end they agreed to a short payoff for 10 cents on a dollar.  It was not easy and we needed to make changes to the contracts, but 10 cents on the dollar to extinguish the second loan is not too bad. 

San Diego Real Estate