I have observed/tested a similar variant of this, since Stable 0.51 - The difference is simply putting the items down with a subsequent sever restart shortly afterwards. Depending on the timing of the restart (a difference of seconds): none, some, or all of the items dropped will be duplicated. It may also result in items disappearing completely, from the floor and the character. I also notice that the entire server's persistence is reset/crashed after performing this multiple times, perhaps attributed to an issue with abnormal rare loot saturation (wild guess).

I also experienced this. Steps to reproduce:

1. Pick up a secondary weapon.
2. Red X to drop it - it quickly disappears but shows up at the bottom of Inventory as Inspect only.
3. Drag it from Inventory into the hands slot - When you Red X it drops as Inspect only.
4. Drag another item into the hands slot (I used a Kitchen Knife) - the weapon disappears again and is back in Inventory as Inspect only.
5. Drag the weapon into the hands slot again - the weapon appears in the Vicinity and in the hands slot. You are now unable to Red X to drop it.
6. Drag another item into the hands slot (I used a Kitchen Knife) - the weapon appears in the Vicinity and the Take option is back again.

Note: For step 5 above, you can also drag the weapon up and out of the Vicinity UI window, as if to move it - now the weapon also has the "Take" option.

Still confirming this occurs as of 12/6/2014.

Confirming this condition still exists as of 0.51 Stable.