There is no such thing as a complete, exact reincarnation of a person, or anything for that matter. Similar to how if you cloned your body, it wouldn't be the exact same as your current one... it wouldn't be YOU (by YOU I mean you wouldn't be experiencing the clone's life in first person, like you are this one). it would also be different in many other ways. reincarnations are purely made up because somebody finds similarities in himself to another person. There are certain "spirits" or "essences" that live on and you see in aspects of different individuals throughout time, in personalities, behaviors, intelligence, appearance etc... But you never see 2 individual things that are completely identical in all ways. The whole "no two snowflakes are the same" is always a facepalm, because no two separate things AT ALL are the exact same. It's impossible, or else they wouldn't be perceived as being two separate things
With that said, we are all "reincarnations" of the same thing. It's the conscious self.. Infinitely dividing, replicating, creating new, expanding in any and all directions it finds etc. Separation and individuality is an illusion... There is only one "soul".
So, nobody is a reincarnation of another human. We are all reincarnations of the original source, which constantly evolves.