A character is transported (or otherwise somehow travels) to a Parallel Universe
, or to another dimension, where they meet version of themselves. The counterpart may look similar, or have a similar name (possibly made up). They may have similar interests or behavior, or may even be gender flipped.
Usually, though, it is a combination of any of these. If the character is time traveling,
expect the "counterpart" to be the traveler's relative, though this isn't mandatory.
Related to Cuckoolandian Counterpart
, except that oneself in another universe isn't necessarily wacky or strange, they just bear a striking resemblance to the particular character. Compare Future Me Scares Me
and My Future Self and Me