I find myself doing this thing from time to time, in which I, roughly, accuse a photographer of copying a picture that was made later.
This is one of the more bizarre and fascinating phenomena which happens in photography, though. Obviously it's not literally true, but it happens anyways. More than we might imagine, I think.
It occurs because of several things which are more or less unique about photography. In the first place, we all tend to make quite a few pictures. Maybe dozens, maybe 100s of 1000s, the point is, rather more photographs than drawings, short stories, poems, or sculptures. In the second place, we're all taking pictures of the same world, with the same people and things in it, all behaving more or less the way they always do.
The effect here is that it's remarkably easy to produce an archive of pictures that contains some pictures that are vaguely reminiscent of, well, of practically anything. There is a certain sameness that occurs over and over, all the moreso within a specific genre or location. Two people doing street photography in Chicago are practically certain to shoot a fair number of similar pairs, pretty much no matter what.
The second wonderful thing about photography is that the edit occurs later. Often much later. These archives lie around for days, weeks, or decades. An archive of raw pictures isn't anything, no matter who shot it, after all. It's just a bunch of junk until someone goes through and pulls an edit out of it.
As a result, it is easy, indeed common, to see someone shoot a bunch of work in 1950, or 1970, or 2010 and let it lie fallow. Someone else then takes some pictures 10 years later, which are then published and become well known. Finally, someone goes through the original archive and finds, unsurprisingly, some pictures that look a bit like the ones shot 10 years later, and publishes those. Those pictures make it into the edit specifically because they cite the ones shot later.
This is usually ignored in the hopes, presumably, that nobody will notice. One could trot out the argument that so-and-so actually prefigured the work of so-and-so, and I dare say the argument has been made (it's jolly compelling if you're not attentive!)
The trouble is that it's not true. While the early photographer is of course not copying the later one, the later editor frequently is copying the earlier one. There's no prefiguration here, it's simply a citation of what is, in a meaningful way, an earlier work. Whether it be plagiarism, homage, or merely a reference, well that depends as always on what else is in play.
As photographers we tend to place too much weight on the moment of button-press. That is, often, not really where the work is done. Often, that's just raw material to be used later.