There is insufficient evidence to prove that there are at least six people in the world who look alike.
A Plus article states that there are probably seven people in the world who look just alike and some individuals were on a mission to meet them. Additionally, the article states that a month does not give much time to search the world for someone who looks just like you. That's why they were stunned by some of the results.
However, there is no credible source to prove that six people in the world would look alike.