Apple has just released their first update to iTunes 11, adding the ability to display duplicate songs, and fixing a few relative minor issues with iTunes 11.
This update to the new iTunes addresses an issue where new purchases in iCloud may not appear in your library if iTunes Match is turned on, makes iTunes more responsive when searching a large library, fixes a problem where the AirPlay button may not appear as expected, and adds the ability to display duplicate items within your library.
The fixes were previously mentioned as forthcoming in Walt Mossberg’s review of iTunes 11. The update is available now via Software Update on your Mac, or as a direct download from Apple’s support website.