I'm pretty sure this is a thing someone has thought up in the past, but I'd like to bring attention to it.
as far as I've been able to find (and do correct me if I'm wrong) there isnt anything tangible (then again when is there ever in this franchise istg) that tells us that the vs and the one you should not have killed are the same person.
well it's a widely accepted thing and logically makes perfect sense. but if they're different it could explain some inconsistencies such as the gender of the vs/oysnhk or the age or the general plot function.
it's possible that toysnhk is charlie emily. in fnaf 6/ucn we're pretty much explicitly told that charlie does not want anything to do with William, just for him to leave her alone and get out of her way. if you subscribe to the charlie is afton's first murder theory, it could mean in the sense that she was his breaking point. he should not have killed charlie because it led to the whole tragic story of the franchise after the death of cc.
another really valid theory is the Michael is vs theory. there is so much evidence to back it up and at the end of the day it just makes more sense than it does for a random kid named Cassidy to hold a personal grudge against Afton to hold both of them in eternal hell. like.
here's a great google doc explaining that theory
at the end of the day, we have never been told that golden freddy kid, vs, and toysnhk are the same. I'm also not saying that charlie is toysnhk or that michael is 100% vs. just that looking at these problems from new angles open even more doors to check out.
anyways there's my random rant for the day, thanks and yw