I was having issues with the K40 cutting aline twice, with the second cut being maybe a few pixels outside of the first. This made for cuts that did not necessarily penetrate the whole thickness of the substrate (1/8" plywood, and in particular, 1/8" mdf) and when it did, it was a burnt and ragged cut.
As usual, I've been using LaserDRW, the stock software that comes with the K40 until I can find the time to upgrade. It is as I've stated before a stripped down, very simple software with no bells and whistles. It does have its limitations.
The double line issue was from LaserDRW interpreting a line as basically a shape, albeit at thin shape. Not matter how thin I made the line it was essentially cutting both edges of it. The solution is to create all shapes with a solid fill. That also means anything inside the shape needs to be a "knockout" if you wish to cut it.
From there I create an engrave file as well, that is if there is one needed. In this case yes. I saw each of the two Illustrator files as the .svg format and bring them into Inkscape
Here are the two Inkscape files side by side. Registered on the same reference point. Unfortunately, many times after these have been converted into LaserDRW files in Inkscape, the register or alignment does not match up.
My solution is to open one of the files in LaserDRW and copy it. Next I open the second file and simply paste the first graphic into it creatine a "second" layer.
Finally I carefully align the two files up manually. I send the file to the laser and cut the outline first. Next I delete it and finish up with the engraving. Seems to work fairly well, albeit a tad cumbersome compared to being able to burn right out of Illustrator as you would be able to do on lets saw a Universal Systems laser. My first experiences with laser cutting and engraving were with such a system, so this has been quite a learning experience.