2 X axis, independent but simultaneous, cutting plotter. How?

Hello All!

-I’m trying to build a drag knife cutting plotter to cut out number bibs for marathons. Typically 7.5”x7.5”, four holes and rounded corners. (Like picture attached.) Out of a thin film material.

-I’m wanting to make this cutter run at incredibly fast speeds to cut these out in under a second each.

-I plan to use ClearPath motors, v-slot framing, and probably an Arduino(s) to control it. Also, using replacement parts from off the shelf cutting plotters.

-The fun part. What would be the best way to give this plotter 2 X axis carriages that can work independently but simultaneously, and yet share the same Y axis? (For the purpose of speeding up the cut and reducing rapid forward and back movement of the material.)

-Similar to how this openbuild’s dual X carriage setup looks: https://youtu.be/3gpeDRt4V6I?t=10 But with a plotter pinch roller in the Y axis.

-Hardware isn’t an issue, and getting the straight cuts is fairly straight forward. Just linear G-code or direct servo commands.

-What I don’t know how to do is write G-code or commands to get the simultaneous curve and hole cuts? I’m trying to get the “X1” head and “X2” heads to cut in the order labeled in the graphic. Green is the X1 head only. Red is where both X1 and X2 are cutting together. The Y axis movement is shared for those moves, given it’s a mirrored Y movement.

-Is there a simple way to do this in G-code? Like re-purposing the Z axis….? (The knifes can be controlled by an I/O port.)

-Or just writing motion control code in a Arduino sketch?

-Let me know if you have any questions, and I appreciate any input.

Tim