I found
this topic helpful.
Finding duplicates is probably easier than figuring out what to do with them. I have plenty of duplicates, but I generally want to keep albums intact. Not so much so "best of" collections, but if the track from that album is of better quality (some of my older stuff was ripped at a low bit rate), what am I to do? In the end, my solution was to keep all the duplicates, but to replace the lower quality ones with the better quality ones—based on significant differences in bit rate. I had to take care the two files were really duplicates and not valid variations of the same piece. I filtered-out live albums as best I could, and then just paid careful attention to album titles and track durations as I sorted them out.
I realize this is the opposite of what you want to do, but now I have to finish the story...
I soon discovered MC didn't offer any easy way (that I could think of) to replace one file with another,
and keep all the library information intact. So I wrote a simple
AutoHotkey script to copy the pathname of the selected track as
source and the pathname of the one below it (the list is sorted so it's the one with the lower bit rate) as
destination—and then execute a
FileCopy source destination.
So now I've still got lots of duplicates, but they're the best quality duplicates available.
My albums are still complete, which was my main concern. If I want to play by smartlist, I no longer have to worry it's going to pick a lower quality duplicate. Conversely, I can eliminate duplicates from a playlist without concern the better version will be excluded.