Okay, so I (finally) figured out how to make (rather simple) presets. And while I was looking through some presets I found on dA, I noticed that some of them had two different sides. I don't know how to explain it.. They had, for example, a marking on the right side of the body / head that wasn't on the left side. Or the eyes had different colors. Things like that.
And I was wondering if someone of you could tell me what I have to do to make a preset like that.