I'm not sure if you're referring to the NintendoAge database or NGD's list. NGD's list doesn't list every seal of quality variant, probably to keep the list a decent size. He just simply says "You will find that most games released before March 1989 and re-released after March 1989 have both seal versions.". So if you're insane enough to actually want both seal variations of a certain game all you need to know is the release date.
That is not to say NGD's List has every last variant, but it's more than enough to keep a person busy for a long long time if they are in to variants. There are almost certainly some other variants that have not been caught yet. Like I came across a Wizardry cart with a silver "battery backup label" (on the rear) not long ago, made a post about it
here. Whether it is a legit variant or something else (read that thread for more info) can't be confirmed unless someone else can find another with a similar silver shine. I personally don't know what to make of it, either way it's only worth a few bucks. :P