Keen GBC Versions
There is only one known version of Keen GBC, which is the one commercially released in 2001. This could be considered v1.0, but as there is no known way of obtaining the version number or revision code, this number could be incorrect and there may also be other versions in existence.
However, according to GoodGBx, the complete list of Game Boy and Game Boy Color games, there are also two trained versions of the ROM. One is by Venom, and the other is by Teksteppa.