The doppelgänger — defined by Merriam-Webster as a “person who resembles someone else, or a ghostly counterpart of a living person” — is suddenly unavoidable. Social media platforms are crowded with videos of “that moment when” a pair of uncanny look-alikes come face-to-face at a friend’s wedding, or in a Las Vegas swimming pool or on a plane. A Taylor Swift doppelgänger has collected 1.6 million followers on TikTok, while the real Ms. Swift performs multiple alter-ego versions of herself in the “Anti-Hero” video.