Cloning has far too many complications, at least in it's current incarnation, to be possibly good. Just one:
In-breeding only causes problems (physically, morally, well, eww) because it accentuates the genetic flaws of both parents, which makes the offspring particularly vulnerable/weak/less capable in certain areas. Now, if you had a cloned person with those same flaws, you have bypassed evolution (survival of the fitness.) The point of inter-breeding is that you can stamp out, progressively, as many faults within a species as possible. Now, let's say that someone's vulnerable to smallpox. They get cloned. Now that person goes out, gets a spouse, and has kids. All of a sudden, you have a
lot more people running around with this same vulnerability. Easy pickings for some terrorist.
Just a note: I don't believe in cloning humans. Livers, kidneys, hearts, embryo research, sure. But in humans, you find that one of their most important needs is social. How can you possibly be expected to live a normal life when you are a mere "copy" of someone else? You can't live life to the fullest, because, even if only mentally, you are not your own person.