Ahh, okay, I think I understand: you are laser carving the entire surface of a piece of wood to use as your printing block and, you need matching designs carved on two identically-sized boards.
This is likely a job for a jig. If you have calibrated your machine, you can likely get very good visual registration with the camera but, probably not hairline registration, which will likely show with what you are describing.
There is quite a bit of discussion in the forums on various registration techniques. Here is a tutorial on the basics of how jigs work, which you can likely adapt:
Searching on “registration” and “jig” will get you many more discussions with variants.
I would probably include an outline vector the exact size of my board in my artwork. I would put down a sheet of paper in the machine, doing something to attach it to the bed (painters’ tape, removable adhesive mat, etc.) and, use the laser at a low power to mark the outline.
I would use the outline to position a corner bracket piece to the outline. I have some acrylic rulers with magnets I made for that purpose but, you could just cut a square out of MDF or Draftboard and, lock it down with honeycomb pins or tape. The key is for it to be fixed to the bed so you won’t move it accidentally.
Then, you can then disable the outline vector in the Glowforge user interface and, carve your design. As long as you do not move anything in the machine or in the software, it will cut and engrave in the exact same spot.
Another simpler approach would be to use a board larger than what you want for your final block and, cut the final size piece out as part of the same job where you carve it. Then, the blocks should be as well registered as your original files.
In my experience (and this is not my primary specialty), when you are trying to do hairline registration, you usually need some way to make adjustments at print time to get it spot-on. Visual alignment with a calibrated machine should get you there if you can adjust the printing position of the second block by a couple millimeters at print time.
Most of the time, when I am attempting what you are describing, I have just done a flood fill or print of the base color, then over-printed the second color with an opaque pigment-based ink. Hairline registration for something like what’s in your image can be difficult under the best conditions.