I had this dream a few weeks ago and it was very troubling.

I was walking around, and every person that I saw had a double right next to them. Some of these people were familiar - friends, people from back in high school, people that I recognize from my neighborhood - others were strangers. There was no rhyme or reason to the characters that were present in the dream, the only thing strange were that there were two of everyone.
A voice said to me: "There are two of everyone. Would you like to meet yourself?" I sensed that my double was neerby, and I grew very frightened, and started trembling all over. The shaking woke me up.

What this means is that everyone has a dark side (the shadow). The fact that you are frightened to meet your double suggests this is the case. There is a part of your personality that you are not willing to face. This dark side could be rage, fear, or lack of confidence.