Help with sketch image trace in illustrator

Hello everyone,my name is roberto.
I nedd some advice and help. Firstly im having trouble with tracing a handdrawn sketch in illustrator. The thing is that my son drawn a sketch on paper. I scanned it en opened it in illustrator. After that i made a image trace to get the outlines and expand it. Ok so far so good.after expanding i saved it as a dxf file,because i want to cut the drawing on vynil and press it on a shirt. The trouble is beginning at the cutting part. But what i get is double lines in tge cut proces. Also a lot of double lines after the tracing and expabding. Is there a way or technique to clean this out. And is there somebody who knows something about this problem of mine.

Thanks.gr roberto