Bukkit

PLEASE FILL OUT ALL THE INFORMATION BELOW! IF YOU DON'T DON'T EXPECT IT TO GET FIXED!

What steps will reproduce the problem?
1. Put something in your inventory
2. Change worlds (I was using /mvtp [world] with Multiverse)
3. Go back to previous world

What is the expected output? What do you see instead?
The item you placed in your inventory should still be there, but it has not been saved. If I place an item, log out, and proceed through the steps, it saves.

Have you tried the latest version of MultiInv from http://build.yu8.me:8080/job/MultiInv3/ (If not please try it to see if it solves your issues)?
I am using the latest build.

You can either fill out the information below or use the plugin DebugReport to generate a report:
http://dev.bukkit.org/bukkit-plugins/debugreport/
Download and install, then wait for the error to occur. Once it has do the command /multiinv report to generate a complete report.
The report file will be in the DebugReport folder.

What version of the product are you using (if you say "latest" you will NOT be helped)?
3.3.6

Do you have an error log of what happened?
No errors occur.

What are your world folder names (with proper capitalization)?
I was switching between a world named Lobby and HCF.

What is the contents of your config.yml and groups.yml?
config.yml has not been touched, groups.yml has each world using its own group. (I don't need any sharing between worlds.)

What is the entire list of plugins on your server (doing /plugins on the console and pasting the output is a quick method to do this)?
Plugins (44): VethragePracticeManager, WorldEdit, SpawnTP, Essentials, VoidWorld, GroupManager, PerWorldPlugins, PlugMan, WorldBorder, LaunchPlate, NametagEdit, BuycraftX, Votifier, WorldReset, WorldGuard, Multiverse-Core, EnchantLapis, EssentialsProtect, EssentialsChat, EssentialsAntiBuild, iConomy, ViaVersion, VethrageKits, Multiverse-Portals, Tablist, Vault, GAListener, PVPMoney, HideStream, EssentialsSpawn, UltraCosmetics, LiteBans, ProtocolLib, AAC, Citizens, Factions, CommandNPC, MinigamesLib, MGSkyWars, CombatTagPlus, WorldPos, TuxTwoLib, MultiInv, VethrageCore

Please provide any additional information below.

I got the same Problem.
Some of my players can duplicate their inventories when switching worlds:
1. Put some diamonds from your inventory to a chest
2. Go to different world (with another inventory)
3. Go back to first world: Diamonds are back in your inventory (and in the chest)

BUT: Not all players can do this. I couldn't figure out, why only a few guys have this bug.