[MCPE/MCJE] Minecraft Glitch - Duplicating Items

NOTE: NOT ORIGINAL. (I forgot where I found this from though)
Old video. Works for a wide range of versions. This can also be done in other devices and in Java Edition too, however it's harder.
Done through a nether portal, a chest, and "crashing" the game.
This happens because of your inventory not syncing with the chest.

[@glubhux]

Proof that this glitch still works in 1.21 (and may persist for a very long time)
ruclips.net/video/uaxL2i_8sZA/видео.htmlsi=mK4pwLI1adtIUL6K