While I’m using V. 2.4 (926) … I noticed in a 3 different files duplicates of component glyphs that are defined as n0-export !
Strangely the duplicates bare the same name NO extra suffix (.001) and are displayed in the same font window !!
That sort of thing should not happen by accident. You might have generated them inadvertently. Remove them, and if they come back, try to remember what you did.
In my experience it’s usually a mistake during a batch copy/paste that only gets noticed later.