I have progressive insurance and the broker had to manually override the 17 digit VIN requirement by adding a string of 1's to the end of my VIN, bringing the total to 17. Vehicles before 1983 have a 13 digit VIN. 17 digit VIN allows for one VIN to be good for 30 yrs, then it repeats.
As far as MVA/DMV, they issue paperwork with the VIN as stamped in the vehicle. They may add 1's to the end in the computer, but it isn't printed on the title or registration, or that is the scenario in MD. Practices are similar amongst states, following the Federal government guidelines.
Did you have an issue with the DMV in your state? If so, try a new clerk at the DMv or the supervisor or an off-site 3rd party tag and title company. If you haven't had any issues, no need in worrying about what might have been. My $0.02
I called the MVA in Glen Burnie about this, spoke with a specialist and she said just file the title as it read. SIX digits. Never even had to get it inspected under historic use (I can always upgrade when I finally get the backup lights wired in if I lose my mind or win the lottery, it's like another $100 a year).
I went through a local tag agency, they typed up papers, took 'em to Glen Burnie, MD MVA, got tags/registration back in four days. Title in about two weeks.
What's on the title? A SIX digit registration number. It was what was on the original Montana title. Machine came out of Ft. Lewis, WA where it was refurbished in late 2006. I bought it in late September.
I didn't have to spend a minute in line at the MVA. Worth every penny at the agency.
Oh, and I insured through GEICO. Did both my '15 Tacoma and the humvee and saved $600 on the cost of insuring only the Tacoma through USAA. Same coverages, too. They didn't have a second of heartache over the six digits, either.
YMMV.
Norm