It clearly depends how your contract is written. My first question is your buyer broker should be guiding you through this process, if you do not have a buyer broker and are doing it on your own, you may want a lawyer to review your contracts to protect you. If your contract is contingent upon the release of another contract by another buyer than you should put your request in writing if it that 1st contract has not been released. If the seller entered into 2 contracts, that is a question ofr your lawyer. My main advice is what ever you do, do it in wroting and keep make sure all coorespondance is in writing in not over the phone.