Minecraft wiki entry for Block_and_item_duplication, associated text: 1 Uses
2 Legitimate Duplication
2.1 Dirt Duplication (Both editions)
2.2 Infinite villager trading 1.16+ (Multiplayer only)
3 Java Edition
3.1 Unpatched/Working
3.1.1 Singleplayer
3.1.1.1 Basic Save File manipulation
3.1.1.2 Alt+F4 v2.0 - Task Manager
3.1.2 Unknown/Unpatched (SP and MP [may be patched on MP])
3.1.2.1 Unpatched 1.16.5 MULTIPLAYER duplication (Explosive fireworks + elytra)
3.1.2.2 Dirt Duplication
3.1.2.3 Lead Duplication(note: does not work in 1.16.4)
3.1.2.4 ALL Item Duplication Glitch (Patched on spigot & paper)
3.1.2.5 Carpet Duplication Glitch (Patched on paper)
3.1.2.6 Dragon's Breath Duplication
3.2 Block Duplication
3.2.1 Unpatched
3.3 Book Mod (Patched on Paper)
3.3.1 Using Shulker Boxes (Patched on spigot)
3.3.2 Carpet Duplication
3.3.3 Patched (Paper)
3.3.3.1 Rail/Carpet Duplication (Unpatched in Paper Build #358)
3.3.3.2 TNT Duplication (Patched in Paper 1.15.2 Build #350)
3.3.3.3 Gravity Block Duplication (Patched in Paper 1.15.2 Build #358)
3.3.3.4 Tripwire Hook Duplication (Works vanilla 1.16.3) (Patched on Paper)
3.4 Patched/Non-Working
3.4.1 Singleplayer
3.4.1.1 Alt + F4 Method (Patched 1.13)
3.4.2 Multiplayer
3.4.2.1 Deadly Method (Patched 1.15)
3.4.2.2 Same Player Twice (Patched in virtually every server)
3.4.2.3 Donkey Inventory Oversight (Patched in 20w16a and in Paper/Spigot 1.15.2)
3.4.3 Both
3.4.3.1 Bundle Duplication (20w45a to 20w48a)
3.4.3.2 Baby Piglin Item Dupe (Patched in 1.16.3)
3.4.3.3 Zombie/Drowned Method (Patched)
3.4.3.4 Chunk memory overflow (Patched 1.15)
3.4.3.5 Dropped Items (patched 1.13)
3.4.3.6 Piston Duplication (patched 1.16)
3.4.3.7 Crafting Dupe (Patched 1.12.1)
3.4.3.8 Using Dolphins(Patched 1.17-pre2)
3.4.3.9 All Item Duplication Glitch (patched 1.17.1)
4 Bedrock Edition
4.1 Unpatched
4.1.1 Dirt Chest (works 1.16.1+)
4.1.2 Chunk save stating
4.1.3 Beacon + Pocket Edition
4.1.4 Fortune on Flowers
4.2 Patched
4.2.1 Gravity Block Duplication (Patched on 1.16.200)
4.2.2 Anvil Duplication (Patched in 1.16)
4.2.3 Anvil Naming (Versions 1.5.1-1.16.0) (Patched)
4.2.4 Donkey + Looting sword (patched 1.16)
4.2.5 Piston Chest (Patched in 1.16)
4.2.6 Rapid Dispenser (Versions 1.5.1-1.5.2+)
4.2.7 Bed Duplication (Patched)
4.2.8 Ore Duplication (Patched)