Doppelgangers are often used to refer to an exact double of a living person. However, there are several synonyms to describe this phenomenon. One term is "twin stranger," which refers to a person who looks very similar to another individual but is not related to them. Another term is "alter ego," which is a distinct personality or character from someone's normal persona. There is also the phrase "lookalike," which is fairly self-explanatory. Finally, some may use the term "clone," although this usually refers to a genetic copy rather than a physical duplicate. Overall, there are various ways to describe the eerie experience of encountering someone who looks remarkably similar to oneself or another person.