mirror image

A person or thing that has or represents the same characteristics as someone or something else. Over the years, the young girl became a mirror image of her mother, down to the slightest mannerisms. The government's policy is really just a mirror image of their last one, only dressed up in different terminology. The villainous mastermind of the story is clearly meant to be a mirror image of Professor Moriarty, Sherlock Holmes's nefarious nemesis.