There are two reasons I installed a second z-axis; one reason was to balance the weight of a direct drive extruder I planned to install. The other reason was to balance the weight of the x-axis in general. I noticed in December that the axis was lower on the right side of the machine by about 4 mm. Considering that my first 3D printer was about 13 inches wide with dual z-axes, I was always leery about having a printer with a wider width and one z-axis. I suppose this upgrade was inevitable.