Goes back to the Greek Ship of Theseus. The ship was at sea so long that the individual boards of the ship started have to be replaced, and, they were replaced one by one, until all the original bits had been replaced
The owner of the shipyard that had done the work took all the older boards, including the old nameplate, and built another ship, with the same name.
Which is the real Ship of Theseus? The original, or, the one that the shipwright build out of the old parts.
Different subjects, a ship is merely a collection of wood and iron and other plant fibers arranged to perform a function. They do not affix themselves according to dna code. They do not self-repair, or are animated on their own to self determination.
But yes there is a similar problem if this was a case of total replacement in the chimera human. But this isn’t the case of total replacement, only partial transplantation.