What does it mean to dream about someone elses' doppelganger?

I've been having a dream since childhood about my uncle's doppelganger. He looks like my uncle and walks around and does things that my uncle normally does but he has a blank expression on his face and when I try to talk to him he looks at me but never says anything. Then my real uncle will drive up or show up somehow and talk to me and not see his doppelganger. What could it mean?|||I am wondering if you see some kind of polarity in your uncle. Sometimes, your uncle may be very warm and inviting, but sometimes he may seem more distant and aloof. I believe your dream is trying to make sense of the dichotomy.