Fame doesn't always equal birth, but just because you weren't born doesn't mean you can't play a starring role. You just need to play that role under a different name. File it off, slap on a pseudonym, and hey presto! Be yourself In Personality Only.
Contrast with In Name Only, where a familiar name shows up on a very different person. Compare with an Timeline Twin ATL Twin, where the name and content are changed but the role stays the same.