well I've reseached this a bit now too and here are my possible conclusions.
1)It's a Boot--If it is a boot is very well done because these do have boxes and USA liscense numbers, etc.
2)It's a legitamate release never released in America. May have been ligitamtly produced and shipped to Brazil, Mexico, etc, But was never released in the USA according to nintendo's offical USA pdf game lists(not the crappy master list on their webpage) they have pdf lists for nes, snes, and N64. The Snes pdf doesn't not include this title nor the a US liscenee for this game. You can see the pdf for youself here. If you check their pdf's you'll noticed no unliscensed games appear, these are only offically liscensed games.
Now I started out thinking this game was offical due to the USA liscense number and the fact that everything with the game seemed kosher except for the cirular seal of quality which is not normal for US releases, except early NES release which had a circular black seal. Since I noticed the seal I've been trying to find the true answer to this question, and I found the pdf's. I'm still trying to dig through Konami to see if they can shed any light on this, but at this moment I consider it to be one of the 2 things above and not an offical US release.
http://www.nintendo.com/doc/snes_games.pdf
The list lists game title , the company that liscensed it and Month/year of release.