You are correct, but interestingly enough I noted that most of the instance admins would reach out to me when I create my alt to check if I am actually me.
So it is indeed possible, but there are some light checks.
Also with the amount of posts and comments I made on the feddit.org alt, I would have noticed it early.
I just added a note about the feddit.org alt in my bio to make this more clear.
The only thing that we can confirm, is that you are the account you are currently posting on.
It is very easy to impersonate someone in the Fediverse.
Taking one alt example to reply.
You are correct, but interestingly enough I noted that most of the instance admins would reach out to me when I create my alt to check if I am actually me.
So it is indeed possible, but there are some light checks.
Also with the amount of posts and comments I made on the feddit.org alt, I would have noticed it early.
I just added a note about the feddit.org alt in my bio to make this more clear.