Version 41.65 Dedicated Server
It's possible for a single person to dupe items in Multiplayer using a satchel, duffel bag or other carriable container placed on the ground.
Steps to reproduce:
Place Bag on the ground with items in it. Log off the server.
Log back in and retrieve items from bag.
Log off and on again.
Items should now be in both your inventory and in the bag.
If you try and take the items again, or place your items into the bag, they'll 'merge' into one and undo the dupe.
This can be done to consumable items to effectively give a single player an infinite supply of anything.
I've included a video demonstrating this below, including the merging of duped items (Server choice blacked out). It works with non-admin players too.