<VV> Mixed ID tags?

[Grant Young]

Wondering how this can be? The car I am currently working on is a 1965 convertible and that is indicated (...67...) in the large ID tag on the rear cross member, but cross checking the VIN tag on the rail next to the battery, it checks at a 1965 coupe (...37...). Both tags appear to be original, and I can not see where a fender was replaced, nor can I see a reason to switch either tag. Any guesses as to why? 
Thanks,
Grant