What i suspect, it's a bug in the engine that allows you to (sometimes) double jump. Some games have it for a reason, but this doesn't seem to be intended. It requires good timing, and, apparently, when rapidly mashing X button, it doesn't work. You need to press X about as fast as a double click with the mouse button, just a tad bit slower. If you are able to time it correctly, you should hear the jumping sound as if you were jumping from the ground, and a further lift into the air. This allows you to access areas that weren't supposed to be accessed. I got to jump on top of the Beet Hoven maze, for instance. Or the Main hall thing in Guberland.