Items player drops in instances appear in another player's instances.

[ShinichiYao]

If you put some items id in ListOfProtectedItems in General.properties for example: 57.

Player drops Adena when he's in instances finish and leave. Another player get into the same instances and can find the Adena the previous player left.

[Stalitsa]

Tested and the bug is there even if the item id is not in “now know as ProtectedItems = “ in general.properties.
it probably has to do with all items in an Instance world. all other drops (monster drop) destroyed after a while but not the one droped by the player’s inventory.