How about clones that are grown in a few years, or months - I haven't seen what the claim is there - to something looking and behaving exactly like the person they are clone of, and then used to replace that person?

Of course clones are a reality, but it takes as many years to grow that identical twin of somebody as it took for them to grow up, and they'd have to grow and learn in near exact copy of the life their grown up twin did in order to become an exact copy... and not even natural identical twins who have grown together are exact copies of each other when it comes to their character even if they share the same DNA. I'd be more inclined to believe that something like robots that are advanced enough to look and behave like some human well enough that they can fool almost everybody, even people interacting with that robot at close range constantly, were already possible than I am inclined to suspect that kind of "clones" were. Especially since if you started with natural human DNA what you'd get would be a human, with their own personality and their own will, not some programmable flesh robot.

(When it comes to those actual robots this is admittedly looking a bit worrisome https://arstechnica.com/gadgets/2025/02/dangling-twitching-human-robot-with-synthetic-muscles-makes-its-debut/ )