Hi,
It's indeed the same musics. Sole difference is the reorder of patterns in "monster pop" which seem more "artificial", shall we say, than in the melo(n) thing.
I've located this music to be coming from the demo
Crayon Shinchan by Melon, where is stored as Propacker 2.1.
I guess the "monster pop" zik is a straight depack off this production. However, where does the name "monster pop" comes from is unknown.
Just wild guesses, here

Sylvain