Delete duplicates in itunes after duplicates have been verified

I really need help deleting duplicates in itunes. I know how to get to the point of showing the duplicates in which I do have a lot of them. Tooo much to delet one by one. I guess that I am confused that If i selected all that it would delete all the songs including deleting the original song. Meaning not leaving any copy of the song in the library. I have been trying to figure this out. I was thinking that itune should be advance enough to tell when a song is imported that it is a duplicate song and notify one to disregard the song by choice. Things would be a lot easier! I know that my windows player would tell me if a song is duplicated so that I can stop it from being imported to the library. Please help! I have read different comments about third party apps but I'm not to sure what would be perfect to use and I feel that Apple should not leave an option that valuable up to a third party to create. Apple please up date itunes if this is a issues that can be resolved much easier and quicker for users. Thanks