There is some precedent for substantial similarity in certain popular songs, but it is based on convincing the court of the argument that the author of the later work must have had heard the original one (for example, over the radio) and copied parts of it, possibly unintentionally.
However, if it's reasonable to demonstrate that in your proposed case that "someone else" had not seen that particular one-in-a-billion image of dogs sitting on a park bench (since probably noone had ever looked at that particular image out of the billions you generated), then their creation is not a copy of your image ("bits have color" - even if it would happen to be perfectly identical, it's not a copy if it was not actually copied) nor derived work of your image and so it does not infringe upon your copyrights no matter how similar it looks.
If I create an AI that creates billions of different image of dogs sitting on a park bench, and then someone else creates an image of a dog sitting on a park bench, odds are pretty high that it would look substantially similar to at least one of my AI generated images. Would it then be fair for me sue whoever is using that image for copyright infringement?