Fast Track C600 for live sessions

[DOSAMAMUSIC]

I use my Fast track C600 to play live with my band..... I use 6 mixes, 2 stereo and 2 mono....my question is....are these outputs separated or always linked no matter what I do....in some concerts the engineers told me outputs 5 and 6 were the same thing, so I had to pan the channels to extreme sides to separate them....my routing in my daw(Cubase) is perfect and I dont know how to fix that, what should I know, to tell the engineers to make it work properly.....are this channels only stereo or they can also work as mono channels???