Repro:
1. Add a server to your favorites
2. Connect to that server
3. When the screen says "ready" in the bottom left wait 2 seconds then hit escape as many times as you can until you are kicked to the main menu screen.
4. Quickly rejoin the same server.
5. When you connect, move backward and you should see a duplicate copy of yourself.
6. Kill your dupe, take his items.