In the upper right corner, the H90 shows routing information. In Insert routing, the Arrow for series and the vertical parallel bars for parallel.
In Dual mode, it seems to just ALWAYS show the “equal” sign, which makes that information extraneous.
It could use a “1” or “2” in conjunction with the “parallel” bars or Arrow to show if the presets are in series or parallel on the same, indicated path. Or, use the equal sign if they are are different paths.
Or, am I missing something?