Human clones, called identical twins, happen naturally. I've known some, personally.

Artificial cloning in the future is going to become easier the more we understand biology, although exactly what you can do with clones or if it's even useful to do is still unclear at the moment.

Science does not, by itself, draw any distinction between right and wrong. Science cannot measure either good or evil, and therefore cannot tell us anything about the existence or nonexistence of either. Personally, I feel that cloning is dangerous, but haven't otherwise put that much thought into it; I believe we have more important things to worry about. However, this is my opinion, and not science's opinion.