That's ridiculous. The TNG art department consisted of some of the most devoted Trekkies you'll ever find. The model was probably put together by someone like Rick Sternbach or Greg Jein or Doug Drexler, all of whom are rabid Trek fans and technical experts (and Rick actually contributed to the design of the Connie refit!). So the variations must have been intentional.
I can't speak intelligently about some of the models used as decoration on TNG, like the silver refit, except that I do know it was placed in Picard's ready room when the Stargazer model was off getting measured for her 4-foot version. Some of the set decoration bits seemed to appear out of nowhere, and maybe they were put together by the folks in the decorator department. I'm pretty certain I didn't put any together beyond the Stargazer, which was a special fun case. One other clarification; I didn't contribute anything to the exterior of the Refit, though I did help out with a bunch of set-type things.