Allow only one list without automatic delivery

Hello there… I have seen users on several times spamming because there is no limit posting any list without adding a unique key/code to it. I believe that there should be a limit per user to list the same item, unless they actually have a key/code for it.

I attached a long screnshot of this case. Hopefully this affects other users as well and will be a valid suggestion to implement. Have a nice day!!