The best solution is to use an iTunes duplicate remover to find and delete the duplicates.
They take up precious hard drive space and make it less easy to organize iTunes music library. ITunes duplicates are useless if not annoying.
Duplicates in iTunes are very common and can be caused by quite a few things such as buying certain songs without realizing that you’ve already have them in your iTunes, importing songs from sources where duplicates already exist, iTunes glitches, etc.
