Disagree. 99.99% chance the later signed contract said it made any earlier contract/ terms fully null and void. Dealer committed fraud by continuing to process the void earlier dated contract.By the time the second contract is in effect on January 1st the dealership doesn't own the car anymore because there's a contract that said they sold you the car on December 31st. Therefore the second is void.
The issue was solved because a very wise member on this forum ( I forgot who it was) told me that per the IRS, the tax credit does not take effect on the date it was purchased but on the date it was delivered.
That's not quite right. Rather it is the date the vehicle was placed in service.
Line 3 of IRS Form 8936 "Enter date vehicle was placed in service (MM/DD/YYYY)".