So I'm still unclear. Are these the same version of EWJ that are on steam?
Those are emulated Genesis games, yes? So no, these aren't the same version. Interplay's EWJ1+2 is similar to the Genesis originals, but not the same -- one level is missing from the EWJ1+2 collection version of EWJ1, because it's based on the SNES release which also had that level missing, and I'm not sure if the animation is quite as good either. EWJ1+2 does have password save added in, though -- the Genesis version of the first game does not have saving. Maybe the Steam version has quicksaves though, I haven't played it.
I remember having a special edition for Windows 95, I'm not sure if it was only EWJ1 or 1+2. I don't know if I still had it anywhere, but that doesn't matter as it wasn't an original copy.
If if was the Windows 95 version, then it was probably Activision's Earthworm Jim for Windows 95 release. While it released before Interplay's EWJ 1+2 for DOS, it's a much better version of the first game -- it's got better animation, two more levels (the one that is missing from 1+2 because it's based on the SNES version, and the level added to the Sega CD and Win95 versions that for some reason isn't in the collection release either), the expanded levels some people have mentioned, and such. It's definitely unfortunate that Interplay's collection used the SNES version of the first game as its base, instead of the Win95/Sega CD version... oh well.
However, the 1+2 collection does include the only PC version of EWJ2. I don't know if it's the best version of EWJ2, as I think the PS1/Saturn ports have enhanced visuals in comparison, but it is a complete, solid version of the game, so there's that in its favor for sure. And also, it's hard to get EWJ for Win95 to actually run correctly on a modern OS -- I haven't managed to get it working on Vista. The game starts, but the sound effects are very buggy and either stutter or crash the game, and it won't go into fullscreen or recognize my gamepad, either.