Authority to accept an affer can be obtained by a power of attorney. Besides, there are several types of auctions such as an absolute where the seller must take the highest bid regardless of price. This would be a clause in the listing agreement between the seller and the broker.
Anyway, I cannot see why a broker or agent would need an auctioneers license. However, I do see where the auctioneer must be required to have a real estate license.
But to answer the origonal posters question, check your states license law. I will be getting my Georgia License next year so I am interested to know. Keep us posted.
Having been a licensed auctioneer, there is one fundamental difference that keeps real estate brokersa from having an auction like environment:
The auctioneer is empowered to accept a contract on behalf of the owner.
A real estate broker can only present offers to the owner for their acceptence, rejection or counter.
Now not all states license auctioneers, but don't have an auction like event in a state that does have licensing.
The original scenario if done as a sealed bid sale and would be legal for a real estate agent.