Taking from previous posts to put on end to the confusion.
Metadata should be Butterfly (Prologue Mix) since that's how it's presented in official and trusted sources and also because that's the most easily recognizable way of citing mixes. Do not nitpick too much, as long as the song is properly cited it should be just fine.
Goes back into lurking
edit: Pls don't fight over a capitalized m although M is the correct way to go