The original soundtrack for Lemmings was a bunch of midi remakes of pop songs. With a few weeks til release they realized what the composer had turned in and the legal issues behind it and turned the project over to a different composer and just said 'fix this' basically. With such a short amount of time left original compositions were out of the question so the idea was reworked from well known pop hits to (mostly) well known out of copyright music. I say mostly because a couple on there actually WERE copyrighted pop music but seemed like they had been around much longer. 'How Much Is That Doggy in the Window' being probably the most prominent example, having been written (and a radio hit) in the 50s but people assume is just an old kids song thats been around forever.