Tbh it will probably be handy to have a spare lying around just in case one of the two you're currently using dies on you. I'm getting another set of Touch controllers instead of getting a third standalone sensor for this reason. A spare set of Touch controllers may come in handy.
i7 5820K @ 4.25GHz | RTX 3080 Ti FTW3 | Gigabyte GA-X99-UD4 | Corsair DDR4 3000 32GB | Corsair HX 750W
SSDs: Intel 660p M.2 2TB, 3x Samsung Evo 1TB | Startech PCIe 4x USB 3.0 | Startech PCIe 2x USB C 3.1 gen2