In any type of data matching you always try to dertermine a unique identifier. For example, for a car it would be a VIN, for a person in the US a SSN. The reason for asking if these are unique to a car was to try and determine whether the possibility exists to trace this back to an original VIN since all of mine were removed from the engine bay. I have no desire for matching numbers, rather I want to be able to trace the history of the car.