So it's effectively 'The Lost Levels', as opposed to the the 'Super Mario Bros. 2' that was actually a remake of 'Doki Doki Panic', which was released in the US and Europe?
Perhaps it's a pirate; as the Japanese version of 'Mario Bros. 2' wasn't seen outside of Japan (officially) until 'All-Stars' on the SNES (I think).
So perhaps someone thought it would be cool to jump the gun and beat nintendo to it.
What do you think & what does VGK (which is written on the cart) stand for?
And PS: Check this out:
http://video.playmagazine.com/forums...php?t6021.html
(about 3 quarters of the way down the page) Someone has found the same cart as you.)
And here:
http://www.digitpress.com/forum/show....php?p=1455209
(search for VGK) apparently their a company that manages repros. (whatever that means; reproduction perhaps?).