Weird - used OctoPkg to remove the Geany editor. After the system notification that it updated the menus, I had TWO DSBmixer’s in the top panel.
Not needing two of them, I just quit a redundant one. All is fine now.
The problem is I can’t reproduce this now. Tried installing Geany and removing it again using OctoPkg, but when the menus got updated, I don’t see any duplicate icons for the dsbmixer in the upper task bar like I did last time.
So, not really a problem, but perhaps a weird one-off occurence I don’t understand. Easy enough for me to fix.