Oh wow, quite recent then, i wasnt expecting that for a 307 !
Propably re-registred from a different reg. Cars in Poland doesn't have 1 registration to end their life. We have to re-registrate, when car is from another city. (Of course, we can keep old plates, but there are some requirements... And besides, Poles don't like driving with "foreign" plates) For example: I buy a car with RP plates, then I have to register him to the KK plates. I have month to do this.