You can find the original uploade here: https://www.pixiv.net/en/artworks/123198675 or the other version: https://www.pixiv.net/en/artworks/123091776 please support the artist fest.
I assume from the other 'petplay' doujin I read. Girl 1 hates herself, so she had herself cloned. She tortures herself because she hates herself, the fact that her clone has the ability to get out of the cage and access to sleeping medication, is just to improbable if Girl 1 didn't allow it to happen.
in the end Girl 1 gets punished by herself because she hates herself and the free girl doesn't have the mental issues that Girl 1 has.
I wouldn't be surprised if the artist fest looked like the girl in the series. who keeps having horrible things happen to her.
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