Accidentally walking by, or deliberately choreographed, ghost images occur in numerous Atget prints. You're not talking about super-slow Daguerrotypes or ambrotypes here. Anyone else would have tossed the neg and taken another shot. I am more than "suggesting" the composition was intended as such. He knew exactly what he was doing, and was a master at it. That's one of the reasons the Surrealists prized his work; he was basically one of them.
A considerable number of his known shots contain brilliantly employed ghost images. Doubtless, not all such attempts would have been successful, and perhaps even the majority were tossed; but the deliberateness of it is apparent in any overall survey of his work.
In the 70's, a number of Atget wannabees tried similar things, inspired by his images. The posted example was hardly unique. But the manner he incorporated all this at the same time into one of his "coin" street/architectural compositions is quite remarkable. Those ghost image passer-bys are staring back at him, no doubt in curiosity, but compositionally as if in fact haunting the scene, just like Atget's uncannily animated statues. If you think it's an accident, try it yourself - not so easy, if one expects anything resembling the same psychological impact. Even the man pulling the cart as a static object is himself a ghost. The more one looks at this picture, the more rewarding it becomes.
Structurally, look at the curved top of a building down the street replicating, and counter-balancing, the curve illumination falloff of his film. Perhaps that is what first tempted Atget to the overall shot to begin with, when the other accents started to congeal. Even Cartier Bresson couldn't have timed the "decisive moment" better. Everything about it is eerie. All kinds of strange things going on, but not in a distracting manner, but all truly revolving around a central focal point.