If you're in the #Fediverse social network your profile is "cloned" in every instance that has seen your content at least once.
If someone is following your account on a specific instance, every single post from that first follower are also "cloned" (sometimes it fails too).
If someone searches for your old post—those you made before someone followed you on that instance—it will also be "cloned".
Even the Mastodon® software itself works that way.
Some Fediverse software also have a public Atom/RSS feed for the entire instance and for each account where PUBLIC content are, well, viewable publicly.
By having an account on the Fediverse social network, you actually gave permission to be "cloned" because that's how it actually works.
You don't like how it works? You have the following options:
a. Go back to any walled networks like Twitter and Facebook.
b. Move to Threads but do not turn-on Federation (it's an opt-in feature).
c. Build your own social network software and platform.
d. Fork whichever Fediverse software you like and delete the ActivityPub features.
e. Live with it.
f. Try to suggest an opt-in feature for your favourite Fediverse software, like how Threads is doing it. (Or, just move to Threads, see option B above)
g. Instead of opt-in, suggest an opt-out feature and ensure it is available during the on-boarding process.
h. An allowlist feature where an account can select which instances they want to federate. (Which will probably make it less taxing on instances, too?)
I think options G and H are the best.
The default is 100% federation. Accounts can choose to opt-out entirely from federation (option G), or create their own allowlist (option H).
Yeah, both options G and H is win-win-win. But that's up to the software your instance is using if they want to implement it.
(I think there were a few forks before with option G? Not sure what happened to them, it's a rarely talked feature because it defeats the purpose of an Open #SocialWeb.)