Someone who mimics what you do or say is a copycat. If your little brother orders fettuccine Alfredo after you’ve already ordered it, you might call him a copycat.
The word copycat is a lighthearted, gently derogatory word for a person who imitates someone else. If you love your friend’s red shoes so much that you run out and buy identical ones, she might call you a copycat. When a criminal commits a crime that exactly follows the pattern of a previous crime, newspapers often refer to it as a copycat crime. The word has been in use in the United States since at least the 1880s.
someone who copies the words or behavior of another