Yes, agents can continue showing a property if there is a contract on it if it has not been ratified yet, or if there is a kick-out. If you are thinking about submitting an offer on the property as a back-up offer or otherwise, you could ask the selling realtor to provide a copy of the face sheet of the contract. All the face sheet will show you is that there is a contract on hand, all the personal information, etc. will be blacked out by the agent.
Hope this helps.
Long & Foster Realtors
Downtown Silver Spring
If there's already a contract signed by both parties, then yours would be the backup contract. But, as noted, lots of contracts fall through. Sometimes the buyer can't obtain financing. Other times, the home inspection comes back with some serious items that the seller isn't willing to address. And if the contract is signed only by the buyer, that doesn't mean anything. The seller can choose which contract to accept and sign.
How can you find out if the agent is lying to you? You can't. But there's no real reason to assume the agent is lying. He/she probably isn't. After all, why would an agent effectively attempt to discourage your offer by saying there's another one already in? All you can do is decide whether you want to make an offer. Then decide how much. Don't get caught up in a bidding war. Figure out how much it's worth to you, as well as your degree of regret if you failed to purchase it. Then make your best offer and see what happens.
Hope that helps.
In a lot of cases, the deal may fall apart prior to getting to the closing table. The seller isn't going to tell you what the previous offers were either. They don't do that because it lets their guard down and allows a potential new buyer to know how low they will go. Even in the event of "multiple offers" they aren't going to tell you what the other offers are either. That's the seller's way of getting more money out of each bidder. Who knows, one person might offer 10k more than the other buyer because of them not knowing what the others are.
I realize your question wasn't directed at a "bank owned" type transaction, but that's where my primary experience lies. I'm also located in SW Ohio. Real estate transactions can vary from region to region.
Hopefully, this helps!
Century 21 Prevete Real Estate