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The only way she could have gotten "hacked" twice is if someone managed to sneak some kind of remote access software on her computer and/or signed up as a different person from her sister's address which I don't believe is known.
If I were her I would copy the Vtuber model directory over to a flash drive then run the windows refresh option to make sure nobody is accessing her system. I don't think the cheap options install like a root kit.