Yes to available on a single machine. Separate folder (path). DO NOT MIX together
Use Create/switch (use existing)to make Calibre aware of the additional library.
Now use the find duplicates (between library ) to identify overlaps.
I would do this from the to be Source Library view. Mark/Decide what you will do (or not do
) with those
You can select as many books as you want, then right-click: Copy to Library:<destination Library> <optional clean out>
I use this all the time with my
Intake Library, where I pound books/metadata into shape, then merge into
Mainlib