My warning was to never let them know of my existence.
I don’t know why that was in plural, but it was.
In any standard plot, letting your clone know of your existence is a way to motivate it to kill you.
Why this is so eludes me. Why would your copy want to kill you, when the “copy” that is you wanted to create another?
But, supposedly, it wants to replace you and become the real person; in the end there can be only one.
It’s nonsense, of course, because writers don’t understand people or even semi-cardboard people like clones. If writers understood people, they wouldn’t be writers, they would be lovers.