If the home seller already accepted the offer there isn't anything you can do.
It sounds like your agent reached out to the listing agent and found out that the property had an offer on it and the seller had agreed to the terms. The property was going to be placed Under Agreement.
At this point, the seller would have had to hold off on the other offer to see what your offer was. Maybe it would be better, maybe it would be worse.
If I was working for the seller and the offer was pretty decent, I would be hesitant to introduce another buyer into the picture. The home seller could end up with no buyers as an effort is made to play them off each other for a better offer. Potential buyers will walk away from a home that already has an offer on it. "I'm not going to pay more money just because someone else wants it" is commonly heard.
If the deal with buyer 1 falls apart, you may have the opportunity to purchase the property. As advised by the other agents, you can always place a backup offer.
In this situation, I would want to know why it fell apart. Maybe a major problem with the home was found that the sellers wouldn't fix...etc. It could be something that would also keep you from wanting to purchase the home.
Best of luck.
Long & Foster Real Estate, Inc
Lehigh Valley, PA