It is not messed up- Those are stereo channels, which take up more real estate on the Circuit board. It also changes how you design an EQ and it's potentiometers when there are two audio paths that must remain apart. Notice that you lose the sweepable mid on those channels! They are assuming that your source will be Line Level and won't need gain. In my day of touring and often encountering Mackie Boards, I kept a handful of short XLRF-TRS cables- if the signal was too hot for the Mic Preamp via the XLR, I could pop one in and use the 1/4" balanced Line input at a 20(?)dB reduction.