It is very confusing to talk about "Aux" in different contexts. There are "auxiliary inputs" (1-6 + USB player), "auxilliary outputs" (1-6 + AES/EBU) and then there are 6 "auxiliary mixing buses" (which Behringer sometimes calls "Matrices".
Even though the Aux outputs MAY come from those Matrices/Auxilliary buses, those ARE NOT THE SAME.
For the sake of clarity, I would suggest that we use AUX for physical inputs/outputs but that we use the word MATRIX for those "auxiliary buses" (which are being sent from DSP1 to DSP2 for the EQ processing and then being returned back to DSP1).
That would make the things much more clear.