I am going to manually remove each duplicate, but my ? is when you click on show duplicates...is that every copy of that song in itunes or is there still another copy that isn't showing when you select this?
Let's say you have 3 duplicates on the computer, when you click show duplicates it should show all 3 as long as the data is the same. So it would be safe to delete 2 of those on that duplicate list.
You can test this by deleting, hitting show all, and hitting show duplicates and verifying that that one is now removed from the duplicate list.