While it's true that Trump reposted a Truth Social post claiming "clones, doubles & robotic engineered soulless mindless entities" have since substituted for the ex-commander-in-chief, according to the linked USA Today article, the same article clearly states that Biden has not been cloned (and is still alive and well).
Trump shares many such baseless conspiracy theories, but there is typically very little real thrust behind them. A New York Times analysis of thousands of Mr. Trump’s social media posts and reposts over six months in 2024 found that at least 330 of them described both a false, secretive plot against Mr. Trump or the American people and a specific entity supposedly responsible for it. No mainstream interview, speech transcript, or campaign document shows Trump asserting the clone theory in earnest or providing “evidence” to support the clone theory.
Other sources have reported on this, like NBC and the NYT.
