I created the whole collection from scratch. I filled all sub-collections manually and then did Metadata retrieval. After that I noticed there are more than 200 items in the "Unfiled items". Many are duplicate items. How did they get there? What's the point of having this directory? .. By the way, did you mean "unfiled" or "unfilled" when naming this directory?
The Unfiled Items collection is an automatically generated collection of items that are not part of any other collection in your library.
What you are likely seeing in the Unfiled Items collection if you think that these do belong to another collection are Duplicate Items. You can quickly find and merge Duplicate Items by opening the Duplicate Items special collection (just above Unfiled Items).
What you are likely seeing in the Unfiled Items collection if you think that these do belong to another collection are Duplicate Items. You can quickly find and merge Duplicate Items by opening the Duplicate Items special collection (just above Unfiled Items).