I'd rather not sign up for a Pin Eight account to edit the wiki there, so here's one that has bothered me for many years:
* Rygar "old man/guru" music vs. Dr. Jekyll and Mr. Hyde (not sure what part of the game). The NSFs I have are Track 5 and Track 1, respectively, for each game (can upload if need be).
Probably not worth mentioning in the Wiki, but thought I'd point it out:
* RoboWarrior (FC: Bomber King) vs. Starship Hector (FC: Hector '87) -- incredible similarities in music style, "instruments" and sounds. Both are Hudson Soft games (and I forget how Jaleco fits into the picture with both these companies), and musician Takeaki Kunimoto worked on both titles. However, the "main" musician for RoboWarrior was supposedly Uhei Inoh. The whole thing could just be the result of using the same music engine and "instrument" library in both games.
Also a link worth pointing out:
http://nesdev.com/authors.htm