I would bet ten million dollars that the answer is yes. But that leads to other questions like “do they care?” A sworn enemy or a dear friend, you can certainly tell by their emotional state, but three random dogs? You’d have to give the dog a reason to want to tell which was which, instead of “lots of dogs!”
Also, some dogs are definitely less nose-talented than others, some are slow-witted, and some just don’t give a damn. My position is, if a dog really wanted to know, they’d know, by smell.
I think it’s fairly obvious that the answer to this is yes. Scent marking is, after all, at its heart a communication method.
This thread is like if a dog was looking over your shoulder at this thread and wondering if the shapes on the screen mean anything to the human, and why the human is so interested in them.
Man, I wouldn’t. First because I obey the old adage of “never bet something you don’t have” 
, but more importantly identification is an issue of cognition as much as it is physical ability. I don’t doubt the physical ability, but I am very uncertain about the cognitive aspect.
Would dogs/wolves get any evolutionary advantage from being able to identify individuals by urine scent-marking, as opposed to just being able to discern individuals? I’m not at all certain they would, which makes me a little uncertain if they can. I really wouldn’t be surprised either way, but I wouldn’t put my own odds on it above a coin flip.
Well, I bet that they can if they want or need to. Whether they do is a question. However, I remember an anecdote in the extremely interesting book Man Meets Dog by the well known zoologist Konrad Lorenz (the guy who discovered ‘imprinting’ among other things) in which a dog of his ‘recognizes’ an enemy from sniffing a post where he had marked.
I see what you did there.
Dogs make friends and enemies among their own kind. If either is in the neighborhood, that’s important to know. So yes, absolutely there would be value in recognizing the scents of individuals.
Recognizing the scents of individuals generally makes sense for a social animal like a wolf. However specifically recognizing urine scent markers as anything other than “other” doesn’t necessarily. They’re not sorting out hierarchy with “other”, just territory and perhaps non-specific signals like breeding status. I don’t know that they really need to recognize them as individuals. And I suspect that whatever different selective breeding pressure that may have applied to domestic dogs vs. wolves is probably pretty well short-circuited by human control of a lot of that breeding.
Anyway, like I said I wouldn’t be surprised if they could. It might be the same pressure that has souped up their nose and social repertoire had the side effect of letting them sniff out individuals at a distance just based on urine markers. I just think it’s a hard thing to prove and it may not be the case.