You're looking at what might be referred to as the real original Lemmings. It had four special levels that used graphics and music based on other DMA titles.
Subsequent versions and ports of Lemmings, though, sometimes removed those levels. My guess is that you had a single-disk version of Lemmings, one which replaced these levels with ones using normal graphics to make it all fit on a single disk (I think one was called "Go For It" and was the "new" Fun 22). The original Amiga version of the game came on two disks and had the special levels.
