I intend to buy only the first car that arrives, and drop the unused spot and refund that deposit. The deposits are refundable. The dealers make no commitments or promises regarding delivery, right? Your contract may be different, but mine says refundable anytime.
I don't see any moral quandry here. Had the dealer said "Do you have a deposit anywhere else?" I would have answered truthfully.
It's just hedging. I don't have enough experience in this market to have personal connections or to choose a dealer with any degree of confidence. They're looking out for their bottom line, and my own limited experience with car dealerships is that they don't often (ever?) look out for the buyer's interest. That's my job.
As for the 'unused' spot, I don't see how a dealership would ever allow someone to sell it or transfer it. They don't leave money on the table. The best I can hope for is that they slide the other deposits up a notch, but I'm not that naive. Nobody offers to pay the difference when they have to sell below MSRP either.