Has there been any movement on this recently? I’ve having this same problem for a quite a long time now. I’ve checked the paths files, and verified that the project only exists in one location (they are on my D drive, and nothing exists in “C:\Users\myusername\Documents\Unreal Projects”
Update:
Figured out what was causing my issue – I had a duplicate line within this file
%LOCALAPPDATA%\EpicGamesLauncher\Saved\Config\Windows\GameUserSettings.ini
Look for the line CreatedProjectPaths= make sure the path written correctly, double check to make sure there isn’t a duplicate present. Once I deleted the duplicate line (that had incorrect forward/backslashes all mixed together somehow), I completely exited the launcher, restarted it, and the library was clean again, no duplicates.