Seller breached-contracted with another buyer to do short sale!

[Allana Alex]

Good day BP members,

Seller and buyer enter into legally binding contract.  Seller later makes themselves unavailable in an attempt to ensure that closing does not occur.  Buyer suspicious finds out through property search that seller entered into a subsequent contract one month after contract with first buyer and does so as a short sale (Second buyer recorded contract, unfortunately 1st buyer did not).  First buyer was giving seller a purchase price that exceeded seller's debt to bank so first contract would not have been a short sale. 

What is the seller thinking?  What is the benefit of breaching contract with higher purchase price to instead do the short sale?