Yeah, I had been wondering about that too for quite some time. I had the physical game when I was younger and I did distinctly remember a level that didn't seem to be there when I was playing on emulator. I recently reacquired the physical version because I'm planning to submit to GDQ and they don't allow emulation, and sure enough, there it was. I've re-split the categories; IIRC there was a level that was only in one of the GB and GBC versions so I'm assuming it's that one.

There's actually a second difference that I found between the versions. The item requirement for Chuckie's segment of the Hospital level is only 16 when I'm playing on hardware, compared to 18 on the emulator.