Galen Govier provides a fender tag service. Check out his website for more info regarding "Galen's Tag Service":
http://www.gvgovier.com/
1 Bad Mirada is correct about the VIN. You cannot legally change the vehicle's VIN number. Problems generally occur when parts from various cars are used in a restoration project. Very often the dash pad is replaced without keeping the vehicles original VIN tag as you have discovered.
From what I understand, if you have VIN issues, you'll need to work through your state's motor vehicle department. Don't be surprised to run into problems, though - especially if the VIN you do have comes from a vehicle previously reported stolen.
Some good news, there are several places on Challenger's where the VIN is stamped or appears. Hopefully, not all the components on your vehicle have been replaced and they are still intact. Check the engine, transmission, driver's side door tag, and the radiator support. I also heard that VIN's have appeared on the left-hand trunk weather stripping rail, but I can't confirm that. The build sheet is another point of reference that was generally placed under the rear seat. Hopefully you will have some matching numbers from these locations to substantiate your vehicle's actual VIN.
I would contact Galen Govier first to see what he has to say about your specific situation.
Good Luck,
Keninpa