A few dupe suggestions

[Jossamations]

11/11 Dupe
an Exploit which caused dying and leaving on the same tick to; not kill you, and drop a random amount of slots in your inventory.
Tutorial: https://www.youtube.com/watch?v=SJb5jHoJG8Y

Chunk Overload Dupe
an Exploit that caused Chunks to reset to their last save due to being overloaded with bloated books
Tutorial: https://www.youtube.com/watch?v=0DE7tDB1u54

Donkey Nether Portal Dupe
an Exploit which involved pushing a Donkey with half a heart into a Nether Portal with cactus on the other side, Which killed it on the same tick it went through the portal, causing it's chest inventory to duplicate.
Tutorial: https://www.youtube.com/watch?v=PS6MTH_eUHs

Thanks for reading! Hope this helps.