as for what you did wrong, that's hard to determine, due to uncertainty over what you mean when you say "trace", and whether you did anything else like mirror the two halves, I can't guess where the duplicates came from
one thing wrong is you should not be using DXF at this stage, you should save and work with CDR or CMX format, then only export DXF for CNC when done with the design
it's composed of lots of disconnected line segments, I can't tell if that's from exporting to DXF, or if it was drawn that way, but generally it is better to create and work with smooth connected closed curves, and save as CMX or CDR, then when you export DXF for CNC, those curves form continuous polylines, which avoids having lots of disconnected line segments, which makes it harder to identify and correct any problems
that design should be just 5 closed curves, which should be easy to work with, but when it becomes 985 disconnected line segments, then it becomes very difficult to work with
when I'm drawing I always work with closed (or at least continuous) curves and never let things get broken up into shorter disconnected segments, and I always make sure all closed curves fill correctly, if not, then something's wrong, so it's largely a matter of trying to avoid problems and catching and correcting them as they occur, so that when finished there are no unexpected problems
otherwise, small problems just gets worse and harder to track down later on
the more you notice problems as they occur, the more you learn how to avoid or fix them, there is no simple explanation on what to do or not do, there is no one right way to do it, but there are a million things that can go wrong, even if you do everything right,
