Can duplicates be identified and deleted in one fell swoop?
Sorta. But I wouldn’t do it.
Go to Albums, choose Focus>Inspector>Duplicates. This selects all duplicates.
Then hit CTRL-A to select all. Edit>Delete Album.
The reason I would not do it is because of unintended consequences. When you are bulk removing stuff, any flaw in software or how the albums are identified has somewhat dire outcomes.
At least inspect all the duplicates before you delete them all.
edit: also note this deletes both copies! If you want to select just one of the two copies you’d need to use a tag or some other way of segregating what you want to keep from what you want to delete. I would guess this is the normal way one would want to do it. If you don’t have too many, you can just click on each version you want to delete. As you do that each album will be highlighted and then you can bulk delete all the selections as described above.
Too late, any way to recover deleted tracks?
From your backups. Possibly your recycle bin still has them.
Going to try it