Earlier quoted context omitted.
It doesn't matter if they exist as exact copies in my opinion. The law doesn't recognize a mathematical computer transformation as creating a new work with original copyright. If you give me an image, and I encrypt it with a randomly generated password, and then don't write down the password anywhere, the resulting file will be indistinguishable from random noise. No one can possibly derive the original image from it…
This surely can't be the case, right? If it was, then what's stopping me from taking any possible byte sequence and applying my copyright to it? I could always show that there exists some function f that produces said byte sequence when applied to my copyrighted material. Can I sue Microsoft because the entire Windows 11 codebase is just one "rote mathematical transformation" away from the essay I wrote in elementary…
Sure, the windows 11 codebase is in pi somewhere if you go far enough. Sure, pi is a non-copyrightable fact of nature. That doesn't mean the windows codebase is _actually_ in pi legally, just that it technically is.
The law does not care about weird gotchas like you describe.
I recommended reading this to a sibling comment, and I'll recommend it to you too: https://ansuz.sooke.bc.ca/entry/23
Yes, copyright law has obviously irrational results if you start trying to look at it only from a technical "but information is just 1s and 0s, you can't copyright 1s and 0s" perspective. The law does not care.
Which is why we have to think about the high level legal process that stable diffusion does, not so much the actual small technical details like "can you recover images from the neural net" or such.