I know the set of notes you're talking about. Music association is a weird thing, but even a set of two or three notes that sound similar to another song will set your brain off onto other songs. The songs are similar enough to be relate-able to one another, but different enough to grow into their own themes. Plus, the samples are for soundtrack only. The Good King Moggle Mog fight song "Seven Jesters" evolves as you progress through the fight. The theme becomes faster as more moogles are felled and the keys change so as to make one think of a merry-go-round (roustabout, carousel, etc.) speeding up and out of control. The "Good King Moggle Mog XII" song is, more or less, a mnemonic device for players. But it's hella awesome, and we can thank Ferne for that amazing rendition (that's him in the recording, you know!)

See, the repetition of phrasing is what sets The Nightmare Before Christmas apart from the repetition through key changes---

EDIT: I just realized that no one cares. I'll be over here. #musicianproblems