Okay, let me be the first to admit that this is a completely off the wall and entirely crackpot theory. Honestly, I consider this idea to be my Sailor Moon equivalent of Timecube, but let's play with the idea that the dub is a separate timeline of Sailor Moon.
So in the Stars season of the original series, Sailor Galaxia tried to stop Chaos by sealing it inside of herself to contain it. However, since Stars was never dubbed, we don't know what happened to Chaos, or even IF the Sailor Moon of the dub timeline faced Galaxia.
My theory is that the dub timeline was created because back during the Sailor Wars mentioned in the Stars season, Sailor Galaxia never sealed Chaos inside of herself. She chose to seal Chaos into a pocket dimension instead.
Sailor Galaxia was never corrupted by Chaos, and she lived a long full life, dying long before the Silver Millennium.
Queen Metallia, being an incarnation of Chaos was never able to manifest herself as a threat to the SilMil. HOWEVER, an Earth Sorceress named Beryl managed to discover the pocket dimension where Chaos was sealed away, not knowing what it was beyond just a powerful source of dark energy, she dubbed it the "Negaverse" and used it to make herself stronger, not really knowing what it was.
And that's where the SM dub we all know and love begins.
I'm sorry, I'm so sorry.
EDIT: I should add that it's not a perfect theory, as it doesn't explain why nobody can ever get the name of Silver Crystal right.
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