If the terms of your contract state that the seller can continue to show and accept back up offers then it is possible. In Pinellas County, FL once a contract becomes effective the property is marked Pending. If it is Active with Contract Pending then it indicates that there are contingencies that must be released before the contract is firm. If it is Pending but Accepting Backups it could mean that it is a short sale, etc. But it may be different where you live so you should contact your realtor and ask what the terms of your contract are. If you have signed a contract and they accepted your deposit (earnest money) then they have accepted your offer. But the rules in states as well as different county MLS systems vary so check with a local Board of Realtors. You do not have your state listed. If you did I would send you the website link. Good luck.