I am using Vienna Organ Player in "regular" (not "spread") mode.
I use a different MIDI channel for each manual / pedal. There are no couplers active.
When I play a long note on the MIDI channel associated with manual A (= any given manual/pedal), and then the same, but short, note on the MIDI channel associated with manual B (= any given manual/pedal other than A), the sound of manual A stops.
I would assume that the different manuals, in the absence of any couplers, can be played independently of each other and do not "steal" notes from or interfere with other manuals.
The only solution I found is to open a new instance of Vienna Organ Player for each manual. I suppose this is not the way it should be. There is no hint in the manual about this issue.
Any comments on this?