Hi, I'll definitely have to give a closer look at it.
In any case, all the versions come from the same game logic. I usually have two sources: one where the game is split in three separate parts and one where the three parts are in the same file. The Amiga and the Atari use the single file source and the game logic is strictly identical. The C64 version comes from a version that is split in three parts, and it should be nearly identical.