Yes, I'm saying turn them off while you are tuning. Otherwise, every time you make an adjustment, the computer is counteracting so it does whatever the NBs are telling it to do. If you leave them turned on while you tune, the car will constantly try to achieve 14.62 unless at wot, no matter what adjustments you make. If you turn them off, you can see what the actual afr is and can tune that to 14.62 except at wot. Then, turn the NBs back on and check it to make sure they don't change anything. This way, the car will run the same whether or not the O2 sensor is working. The only way you know you have a failed O2 is because of a CEL light. If you don't do this, and a NB goes out, the car could instantly go extremely rich or extremely lean. It takes a while to do it right, but man what a difference it makes when you complete the job.
You can have all three O2s installed, just turn the NBs off with your HP tuners when you are actually tuning.