I'm not sure what/what plugin is causing this; people who die in the_end or nether world who teleport back to their place of death are sometimes retrieving a duplicated inventory. I have tried to find out the cause of it and have had no luck current plugins: Orebfuscator, MultiInv, WorldEdit, SpamGuard, Vault, PermissionsEx, Multiverse-Core, Stargate, LWC, WorldGuard, CommandLog, ChatReplace, AntiAd, CoreProtect, DrugMeUp, mcMMO, Mcmmorankup, BookShop, BookWorm2, Essentials, EssentialsSpawn, Multiverse-Portals, RegionForSale, VanishNoPacket, CompatNoCheatPlus, ChestShop, EssentialsChat, Factions, NoCheatPlus bukkit version 1.3.2-R1.0 (Build #02377)
BlakkDock Ensure you have 'MultiInv' installed properly. Since it manages per-world inventories, you could have made a configuration error, or it could just be a straight up bug.