On most servers, duplication is a bannable offense . Many modern 1.7.10 servers use plugins like Spigot or Paper that fix these "vanilla" bugs automatically.
This is the most famous and reliable dupe for 1.7.10 single-player worlds. It exploits the way the game saves player data versus world data. minecraft 1710 dupe work
Older versions had issues with "Wand Foci" like the Dislocation or Equal Trade foci, which could occasionally "bypasses" block-breaking logic to create copies. On most servers, duplication is a bannable offense
Placing this setup on (especially corners) increases success, as different chunks load and unload at slightly different times. It exploits the way the game saves player
When you restart the game and load the world, the items should be in your inventory (from the save) and also lying on the ground (since the world file didn't save their removal). 2. Hopper Chunk-Loading Glitch (Vanilla & Multiplayer)