Mystery: Did Audi ship thousands of cars with same VIN? And why?

The discovery, reported by the German business journal Handelsblatt, was made when investigators searched Audi's audit department for documents related to the Dieselgate scandal during a wide-ranging raid in March. It came after the German Transport Ministry accused the company of cheating on emissions testing for 24,000 Audi A7 and A8 diesels. According to the report, Audi's auditors had the documents about duplicate VINs because they were assessing a "risk of discovery."

Audi professed ignorance, with a spokesman saying, "We are not aware of the fact the VIN numbers have been issued more than once."

VIN numbers are supposed to be unique to each vehicle, with 17 digits and capital letters that identify that vehicle's DNA — including features such as where a car was built, the model year and engine specifications. They're used to track recalls, ownership histories, registrations and thefts, among other things.

Under EU and German laws, VIN numbers are supposed to remain unduplicated for at least 30 years.

Investigators told Handelsblatt they were puzzled as to why Audi would produce vehicles under common VIN numbers.

Audi, a division of Volkswagen Group, in June issued a recall for around 24,000 A7 and A8 models built between 2009 and 2013. It later said it would update engine software blamed for the emissions cheating scandal on up to 850,000 diesel cars.

But the VIN mystery adds a new wrinkle.

If nothing else, the duplicate VINs would make for an interesting Carfax search.