Software problem with dual head laser cutter, can't cut wide items.

I'm having problems programming a dual head laser cutter I recently acquired. The heads are duplicating the cut, instead of mirroring the cut.

First, both heads are the same gantry, so the Y motion is identical. I have a Guanghou Puhan DSP controller. The bed is 1300mm wide. Each head can only reach half the bed. The left head covers the left 650mm, and the right head covers the right 650mm. The problem comes when I want to cut a wide item. I need the left and right heads to cut a mirror image of each other. Instead, the right and left head copy each other. I've gone through all of the software and panel settings, and no luck, unless there's some magic combination I don't know about.

I'm aware that I could cut the left side with just the left head, and then cut just the right side with just the right head. However, that seems pretty stupid. The reason why I got a dual head laser is to cut twice as fast, not twice as slow.

Any thoughts on this? Thanks for your help.