Duplicate songs in Apple Music on Windows 10

I have just "upgraded" to Apple Music from iTunes on Windows 10. Let's say that a lot of songs in my library are under a folder called Amazon because they were bought from Amazon. With iTunes, whenever I bought some new music from Amazon I simply re-added that folder to my library and it added any new songs it found to the library. Result, great happiness. With Apple Music, every time I re-add that folder it creates yet another copy of every single song. Result, great unhappiness. I have the settings set sensibly so that nothing gets copied into the iTunes or Apple Music folder. Why is Apple Music so dumb where ITunes was so smart?

And in reality I have a number of folders that new music can appear in as they are occasionally synced from another computer, so I'm usually not sure exactly where the new songs are, which is why I do what I do. (Sorry for the detail here, but I have noticed a tendency for people who post problems to be lectured on what they should and should not be doing.)