I created a playlist with the Duplicates Manager tool (thanks for the playlist naming prompt!). When I selected one file and use it to replace another, the original file is not removed from the playlist, it just floats to the top with a (!).
Also, while editing files in an auto playlist, I find that if I edit one file in such a way that it will be removed from the playlist, I can use the > arrow to go to the next file (correctly), but if I edit the second file and use the > arrow again, it then takes me back to the first file in the playlist. (To be clear: the tag editor is open the entire time. First file good, second file correct - but it is not shown as selected in the main panel - third file incorrect.)