If the seller sold the same car twice, he is likely to be paying damages . . . Who he pays probably depends on the terms of the first contract. If the first contract wasn't written, we have what we call a "mess." If both contracts are evidenced by nothing more than partial receipts, we have a "real mess."
Attorney fees to sort this out are likely to be more than anyone is awarded . . .
I agree with Mr. Hawkins. I also wonder if the receipts indicate whether or not the "partial payment" or deposit is refundable and the duration that the vehicle is to be held by the dealership and not sold as a result of the partial payment. Look at the receipts and any other documents that may have been signed at the time each buyer made their "partial payment". These documents may answer your questions.
This answer is for general purposes only and does not establish an attorney-client relationship. The law in your state may differ and your best answer will always come from a local attorney that you meet with privately. If you need a Consumer Law attorney, click the link above to find a Consumer Law attorney near you.