This is a good question and a hard one to answer. I'd say that it is definitely possible to recognize another sociopath in real life because I have done it once. But it's also impossible to know whether or how many other sociopaths I have met in real life without being able to identify them.
The one time I recognized a sociopath in real life, the person was of my same general background, education, and was even in my same career, which helped immensely I am sure. I think when you recognize each other, the thing that tips you off the most is watching them perform your same tricks. This must be how conmen spot each other (or at least this is how it is always portrayed in film). There was something somewhat unnerving about our subsequent interactions. With both of us mirroring the other to a certain extent, it was almost the effect you get when two mirrors are facing -- an endless loop with no substance. Still, I think we understood each other and got on well.
The only other sociopath I have met in person is someone whom I had been previously informed was a sociopath. That interaction was in some ways more telling. We come from very different backgrounds, are in different stages in life, and just generally live in two different worlds. I don't think I would have been able to tell whether this person was a sociopath if I hadn't been made aware of the diagnosis ahead of time. The more time I spent with this person, the more I saw similarities, but this person's tricks were a different set than mine -- surely a set more suited to their daily life than mine. We still talk and get along well too, but I think we also can bore each other with our lack of substance and commonalities to discuss. But also we must intrigue or attract the other, because we definitely still play games whenever either of us is in the mood.