I've never seen anything like this before - these two unrelated games (as in, not sequels or companion games) are nearly identical. I don't mean merely similar, but literally the majority of gameplay mechanics are the same.
The monsters are the same (graphics, names, etc.)
The dungeon crawling is the same
The way enemies attack (by charging once you enter a room) is the same
The way your pet "evolves" is the same
Just the names and story are different. There's a couple other differences - MWMW has an overworld exploring part, and MOML lets you build dungeons.
It's the weirdest thing, I've never seen anything quite like it before.