As I understand it, Windows can assign different letters to external drives. If you take an external drive (with your music files) to another computer, it may be assigned a different letter when you plug it back in to your primary computer. This is when the fun starts: MC naturally does not recognize the drive letter. Re-assigning the drive with the original letter can be quite a challenge. So, you reconfigure auto-import to recognize the new drive letter. MC dutifully adds all the files from the drive (the same old drive but with a new letter). Can take a long time! And Bingo! You now have duplicates of every music file in MC. Now you have to delete the original files in MC by means of the "Files" branch of the tree. Seems to be rather a roundabout process, don't you think?
And yes, I have tried re-assigning the original letter in Computer Management (Windows 10), but the one letter I can't assign is the original one (!). Also tried right-click and renaming, but then I get two letters for the drive. No easy way to go back to the original letter (D: in my case)?
Or, am I missing something?