Don't know if that is expected or not?
if you have a window where you have add columns, Add Columns... added (say Length & SHA-1)
& then you do a search with
add-column:a
- so now you have both Add Columns columns (Length & SHA-1) & add-column: (A, in this case) columns
if you then remove (uncheck the column in the right-click context-menu) any Add Columns (say Length & SHA-1),
if you then, keeping the same add-column: search, but change the search slightly,
so if it went from,
add-column:a
add-column:a audio:
that then causes the removed Add Columns columns (Length & SHA-1) to reappear
- even though you had removed them