I have and I've had them verbally tell me, "But I had you booked." when they had not actually finished the booking process. With any form of a verbal hold, they assume they have you on the hook and they can continue shopping for a better deal. That's why I'm crystal clear, your deposit locks the date and executes the contract. First one who pays, owns the date. If they're pissed at me because they didn't do the deal, I couldn't care less.
If that ever happened, I'd gladly refer them to the email we sent them letting them know they were taken off the list because they didn't finish the process