[TRE Cup]

Try sliding your fingers under the VIN # by the smugglers box and see if you can feel if it has been welded in. Also pull the pass side knee pad and see if the # under the glove box matches. I have seen these welded in from other cars. If they don't match, ask for your deposit back right then and there. If not call the police and have them stop over right away for someone selling you a stolen car. Let him worry about it not being hot.

The first sentence is correct advice. The second is NOT !

The factory assigns a production assembly number to the chassis. That number is stamped below the radio , on the metal dash frame. After that the chassis is assigned its vehicle identification number according to the production order.
They never will the same. The factory has records of the two numbers, along with engine and transmission serial numbers.
It is a very good idea to check that the assembly number area has not been tampered with, and removing the kneepad is a good way to start checking on this.

General comments: It takes time to receive the information from Porsche, regarding numbers on their cars. AT BEST; if you have a friendly contact in the dealer system they can only confirm or deny that the numbers match the chassis. Why don't dealers get COA on their cars ahead of time? LOTS of reasons, and i suspect mainly length of time to receive it, some cost, and the fact that these cars are not registered in their name. They are just selling and not hanging on to their product.

Buyers should ALWAYS spend resources to get a car checked out. Reputable dealers/ sellers will welcome dealing with experienced inspectors, independent, or dealerships. If they refuse, then time to walk away