Actually, they have not been able to clone thought patterns and
behaviour, only physical matter. And that shouldn't terrify anybody.
And even if they one day can clone such things, as long as they clone 2
or more of the same guy it won't be any problem at all. Because if there
was someone exactly like you, they would think exactly like you and do
the same things as you. It would want to sit where you are, stand where
you are, eat what you're eating, marry who you marry, to be in the same
place at the same time, in the same way as you. Two such beings will not
last, they will either perpetually fight or be at a loss how to proceed.