1) No, I do not have identical tracks. For one thing, even if it might have happened once or twice, certainly not on every track on almost every playllist. But it didn't: I keep careful watch over the total number of tracks exactly to avoid duplicates (it's a rather large library) with even slightly different tag data, as I correct tags details from time to time - but that's irrelevant to the case. What do you mean by ID?
2)Most convenient would be the window with the list of playlists. Barring that, the one that would let the user to skip going "tools"-"scripts"-"Recreate M3U" every time (for each playlist), i.e., keep your script up. My situation is that I have to fix quite a number of playlists, not one at a time.
If it's convenient for you, we can continue offline and I can supply screen shots or whatever additional info you request.
Thanks for the answer - K.


