Using Boats and Ender Crystals, you are able to duplicate the content of your inventory as often as you want.
Reproduce
1. Make sure you are on a Multiplayer Server and in Gamemode 0
2. Get a setup like the following by stacking up on the side, placing a boat on a block above the Ender Crystal and remove the block afterwards.
[media]3. Get into the boat (or stand on it) and wait a few seconds. You will get kicked for "Flying is not enabled on the server". If you get kicked from the server by (probably) every other reasons such as /kick, /ban, a timeout, normal logout, ..), it will work as well.
4. Relog a few times (the amount of relogs is the amount of duplicated inventories)
5. Get out of the boat and destroy the ender crystal
The server will think that you've died several times and drops the inventory. The player is however not listed anymore and cannot be targetted by using selectors in commands.
The player is not properly kicked from the server.
A Video showing the concept can be found here https://youtu.be/tZnQUtJwnqc
Related issues
relates to
Comments


You extra drops don't come from dying at all – the extra drops come only from the crystal exploding – it doesn't have to kill you.

Exactly Sealbudsman, you don't die from doing that. Only the server thinks so and will drop your inventory.

It's kind of like 2 bugs:
1: sitting in that boat shouldn't kick you,
2: getting kicked shouldn't cause that inventory dupe.

Confirmed for 15w45a also for the normal /kick
command.
Could you please cover the fact that the server does not remove the player correctly from the world please. The player is however not listed anymore and cannot be targetted by using selectors in commands.

Please update the description to something to describe that the server does not kick the player properly

"Inventory Duplication when kicked" would be good I think. Getting kicked by this convoluted method would be a singleplayer example, and using /kick would be a multiplayer example.
– oh shoot wait.. was this ever a singleplayer bug?

I don't think so, however the bug is that the server probably does not remove the player entity after a kick

Please update this report. The title is misleading as like I said (and also MC-94548 shows) this also affects kicking players normally and even logging out. This is currently not covered in the description.
Confirmed for 15w51b
Confirmed. To be clear, the inventory doesn't duplicate until you blow up the crystal and your inventory drops. One duplication for each kick you received, as OP said.
Also you'll get kicked just for standing on the boat that's up there, you don't have to mount it.