What is the best way to delete many duplicate songs

[blusubaru]

No, if you copy them to a new playlist you can't delete them from the library. You can only remove a duplicate from the library folder when selecting it withing the library in the application and deleting. I'm going through this right now. The best way I've found is using the new "Show Duplicates" feature in the edit menu. I then go through and select every other one (hold down apple key and select). Then hold down the apple and delete keys to remove them. You're prompted with the window asking if you want to keep original files. BUT you have to be careful because one file could be linked twice, meaning, if you delete one you delete both from the library and trash the original file. I'm slowing making my way through my 1600+ duplicates.

You could also check out these duplicate scripts from Doug.
http://www.dougscripts.com/itunes/ just type "duplicate" in the search box.