Something seems amiss. I entered a -1 on the X-axis but what I got was an unmirrored leg. However; the leg is not one piece of geometry, but seven. Does that make a difference? Need I Boolean the pieces together before duplication?

Can I Boolean NURBS objects, or must they be converted to Polygons?

Marching blindly forward, I converted the boot to polygons, and the Duplicate Special worked just fine. I then Booleaned to two pieces together. I presume, at this point, I cannot return to NURBS?