Presumably the new DMV VIN & Title mean that they performed due diligence to be certain the cars weren't stolen or otherwise subject to legal issues.
Ford VINs of that era would call out engine & trans IIRC, so a regular Mustang & a Boss 302 couldn't have the same codes on their VIN tag.
Ford VINs are also stamped in 2 or 3 areas including the tag, which is attached to the driver's door.
Whether all that was switched around is the big question, and it's probably unanswerable without sanding down the VIN locations & verifying factory door tag attachment.
At least the DMV VIN makes it obvious that the cars have unsavory history.
IIRC, there was a guy who faked an LS6 Chevelle a few years back, got sued & lost his [censored], but I don't know whether the VIN was addressed or if there was jail time.
Given the values/prices for E-bodies, the guys faking them are playing with fire, yet those cars get exposed here frequently.