How to make an server where if you throw an item then it dupes?

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    hi i am a youtuber named Miney M M and i saw a server which can dupe a item if you press q, but the server is full of admin bullies, if you want to check out-terrekks.aternos.me
    so i wanted to make my own server which dupes
    (the person who will help me will get op, shoutout, much more.