I also would love to be able to have 2 files in the same format in one book entry (adding already existing ones, not converting).
Before this new feature were implemented, I have lost (hadn't deleted an original so could recover) an original book then I converted in the same format.
Now I have some books for example original pdf and converted one and I would love to have one entry for them, instead of making my library twice as big with double entries (also trouble syncing with goodreads and similar if there are a few entries).
I think since it is already allowed to have two files in the same format in the same calibre folder, it could be expanded to just adding already converted files.
Hope someone who is capable will work on this
