Flattening Two Lines Into One

I am engraving and cutting wood but when the design vector cuts, it runs a 2nd pass, thus leaving scorch marks everywhere. When I zoom in on the curve, it has a hairline on the inside and outside of the curve, which explains the 2nd pass. How can I flatten it to one line?

1. First we're going to need to separate the two lines. The best way to do this is either to ungroup the lines by right clicking and selecting ungroup.  If ungroup is not an option, you may see "Break Contour Group Apart". Select this.
   
   
2. Next, with both lines selected, choose the Weld feature in the top menu bar.
   
   
3. Now the two lines should be combined into one line.