Car seller asks unsigned "cancellation form" (widerrufs form) to be sent. Why?

I am buying a car in Germany, from abroad, and seller asked me to send him via email along with the signed contract, the unsigned cancellation form. (widerrufs form)

As far as I know, this cancelation form is supposed to be send, signed, when the buyer wants to cancel the order after signing the contract.

Can anyone tell me why the seller is asking to receive the unsigned cancelation form?

Please note this seller works for the make of the car not just an official dealership.