And if somebody is buying the real one in peru and bring back to usa and try to put a plate on, does the DMV would say sorry but this car is already existing ?
You'd have to talk to someone who works for a DMV in the US and ask about that situation? I think that all the states computers are tied together but who knows for sure? I would presume that the system would show a duplicate serial number in another state but I don't know that for sure.
Some of the smaller states may be still operating under an older system for budgetary reasons?
In NYS, there is no title until the 1973 model year, so essentially you can walk into a DMV office and register it. They have no records of the Ford number like SAAC does.
When the cars were new, that's often how new Shelby's would disappear after they were stolen. The thief would just register the car under the Ford number which would be "clean".
It was even a problem with Cobras. The car could only be identified by the plate pop riveted to the car.
There was a famous case of a 427 Cobra that was a street car. The owner at the time purchased a genuine but stolen VIN tag from an S/C and just pop-riveted on.
The owner sold the car as an S/C. The new owner discovered that it wasn't and sued for fraud.