I agree with Met, but I think the duplication is alright; you should try playing with it a bit. Try playing with the size and transparency of the duplicate and see what happens. It's all about your personal, artistic point of view. ;)
For a first signature, it's really good. (Way better than my first sig. xD)
“I've got my Batman shirt on, and I'm ready to go. JUSTICE! I'm gonna go full on Batt."
Wow! Looks great, especially for your first siggy. ^^ I'm not an expert (at all) on these kind of things, but, maybe make one "Zuko" a little more blurred or faded into the background? Meh, just trying to help.
~“A perfect summer day is when the sun is shining, the breeze is blowing and the birds are singing.”