The practice of placing multiple VIN's on cars, at least for Chrysler built cars, did not begin until 1968, when Chrysler moved the VIN plate to the upper dashboard and stamped the last seven figures on both the engine block and transmission case. Prior to 1968, the only VIN present on the vehicle was the VIN plate in the door jam.
The practice of placing a hidden VIN on any vehicle did not begin until maybe the late 1970's or early 1980's. The standardization of VIN's throughout all vehicle makes began in 1981 with the beginning of 17 figure VIN's.
Unfortunately, most DMV employees were born after the standarization of VIN's. They were all taught that all cars have multiple VIN's stamped on the cars and have no knowledge of the early practices prior to standardization.
All of the original letter series Chrysler 300's built between 1955 and 1965 were identified with only one VIN on the vehicle, which is the VIN plate. The only exception were the early letter cars of the 1950's (I think only 1955's and 1956's) that had the VIN stamped on the engine. THERE ARE NO HIDDEN VIN'S ON THE ORIGINAL LETTER CARS!
On a side note, the term "Numbers Matching" only applies literally to cars built starting in 1968 as an original numbers matching car would have matching VIN numbers on the dashboard, engine block, and transmission case. The original letter cars cannot be truly labeled as "Numbers Matching", even if the original factory installed engine and transmission are still in the same body, because there are NO NUMBERS TO MATCH!
It's time to go back to DMV and give them an education.