I bought one Iceball Trebuchet, and placed it on the wall. Nobody was around so that one was placed by me for sure. I could fire it but could not stow it. Then I found another Iceball Trebuchet in my inventory which I could place and stow. WTH?
When high server lag, you can stow an siege weapon but it looks like its still there but can't be stowed a second time. It can even be fired, but as it gets damaged, the one in your inventory takes damage (as they are the same siege weapon.)
If you place the one in your inventory, the first one will instantly disappear as there is really only one