Please Help with Quick way to Un-do Duplicates

Question

OK, I'm using a Windows PC, with Vista 64-bit.
Music is my life. I have 36,000 songs all in 320KBPS. Since Apple Lossless is mindbogglingly not available in the iTunes store, I use the highest quality of CD-Import I can find.
Not sure what I did, but I was in iTunes and at the top, it started saying "Processing Files" and was counting songs as it processed them. I was thinking "I didn't hit anything? Is this a back-up? What's going on??"
So I looked under FILE>Show Duplicates and I have 26,000 of my song files DUPLICATED!
Here's the Dilemma:
I cannot just highlight them all and hit Delete because "Show Duplicates" shows the original song and the duplicate song on top of one another like this:
POSITIVE TENSION / BLOC PARTY
POSITIVE TENSION / BLOC PARTY
THIS MODERN LOVE / BLOC PARTY
THIS MODERN LOVE / BLOC PARTY
Make sense? If I delete-all, the song would no longer be in iTunes at all.
I cannot spend hours deleting Duplicate songs one-by-one. That would take days! Highlight song, Right Click, Delete, Are You Sure? Yes, Delete.... repeat. Crazy to even think about it.
So... I deleted iTunes. I re-loaded the newest version of iTunes 9 for 64-Bit. It found my songs, but STILL Duplicated instances of songs!
Does anyone PLEASE now a very quick way to Un-do this or delete Duplicates...????

Answer 1

First check your recycle bin. Hopefully your missing album is there and can just be restored.
Now open *Edit > Preferences... > Advanced* tab and click the Reset button next to *Reset all dialog warnings*.
Take a single duplicated track and use *Get Info. > Summary* tab > Where: to confirm that both entries refer to the same file. Now delete the entry with the newest *Date Added* date. This time you should definately get a prompt to keep the file or move to the recycle bin. *KEEP THE FILE*. Check the remaining entry still plays.
Assuming things are behaving as expected you can now select all the recent entires & delete, keeping the files so that the original entries will still have files to point to.
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If you're in any doubt about how all this works then before you start you probably ought to take a backup of your entire iTunes folder. Had you had one you could have simply restored your most recent iTunes Library.itl file in a jiffy.
*Fast backup for iTunes library (Windows Only)*
Grab SyncToy 2.1, a free tool from MS. This can copy your entire iTunes library & any other media folders onto another hard drive or network share. You can then use SyncToy periodically to synchronise or echo your library to the backup. A preview will show which files need to be updated giving you a chance to spot unexpected changes and during the run only the changed files will be copied saving lots of time. And if your media is all organised within the iTunes Media folders then you can open the backup library on any system running the same version of iTunes.
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You might also find the following useful in case you accidentally remove too many entries:
*Adding new items/removing orphans*
Try iTunes Folder Watch or iTunes Library Updater. Folder Watch is much faster on the adding files front, can be set to run in the background and includes a useful exclusion feature, however it’s really slow at removing orphans. iTLU is better for this although doing it manually after looking at a list of proposed removals generated by Folder Watch is probably faster still. iTLU can also be set to update iTunes when you've used 3rd party tools to change tag info.
tt2