Thanks! I am using the formbot printer, which does not have offset information. Of course it does not mean to have Y offset, but small inaccuracies will result in Y offset.
So are you suggesting me to use a caliper to measure displacement between the center of the nozzle holes and enter it as X offset? The issue is that the extruder is not a chimera, where both nozzles are fixed onto a piece of metal, the X cartridge of the formbot is 3D printed and holds two independent extruders with screw and friction, so it is easy to have unintended Y offset.
And how tight the tolerance is required for 2-nozzle operation for the purpose of using the second nozzle to print soluble structure?