The dxf file is 98% OK. No duplicate drawing objects. All drawing objects that are in the file are valid for BCL.
As you pointed out, there is one Polyline that wasn't created correctly. See attachment 2.png below. However, this polyline drawing object can be burned if you create a toolpath with all of the individual objects sequenced together correctly:
Polyline 60 (this object also needs it's direction to be reversed. Assign your tool and press the R key to reverse direction. See 1.png)
Arc001
Line033
Arc000
Line032
Arc003
Line034
Arc002
tp.png shows that I assigned my laser tool to each of the polyline drawing objects (as listed immediately above) and then I typed in a toolpath name and pressed Return and then clicked the TPSave link to save it. This toolpath file.
Here is a Youtube video I made to show you how to do this:
https://youtu.be/c8OdkBsGKEs