PrusaSlicer uses T1 to select second 2 extruder

I'm trying to track down a problem with a dual extruder printer for a friend. If I add a second extruder to my printer profile in PrusaSlicer and select the second extruder, the only difference in GCode (lots of comments changes) is that T1 is added.

I added a second extruder to my profile but I'm using the Virtual print to test. Both GCode (with and without T1) use Tool0.