There have been a lot of mistakes made over the years, one way or the other, and maybe even a few deliberate deceptions. I owned TS39781LO for over 10 years before anyone realized that the number on the paperwork didn't match the number on the car. It just wasn't a problem until the law that your insurance company has to notify the state that you have insurance (the ins co had the number off the car instead of the number off the paperwork). When I reported the issue to the DMV, they just changed the number on the paperwork.
And the Stag I got with LE2013LBW on the plate (which should be a 71 Stag with an automatic transmission) is apparently a 72 or 73 body with a 71 interior, 73 engine and a 72 manual transmission. Obviously a previous owner has assembled it from several different cars.