I just think can be made a very easy system like this.
You count all the items in the world and put this number in All_Items_In_The_World
Every time an item it’s dropped from a chest or mob the item it’s added to a counter, the counter can be global or for each person. If the counter it’s for every person you can then add all the PeopleCounters to have the All_Dropped_Items so you can update the total counter only 1 time every hour/day.
You check every hour/day that All_Items_In_The_World = Previous_All_Itrems_In_The_World + All_Dropped_Items
If the number doesn’t match, that mean somehow was a dupe.
It’s not ok to “hear about dupes” on social media like the stuff comunicate to us.
You need to have a system to check this.
This is a very simple version of a check.