I recently made a request for a livery that I wanted, but later on somebody made a request for the same plane and livery as my request. I also found a request for a livery that was already posted on the website. That made me think about how their could possibly be a system to remove duplicate requests or requests that have already been made.
I was thinking there could be a report button, or something similar to this, on each scenery and livery request. When clicked would give you a sort of dropdown with a few options to click. These could be This request is a duplicate and This request has already been fulfilled. When you click each it could give you a quick form where you would give the link for the request it has duplicated or the addon that has already fulfilled the request. Then the mods/staff could check which request was made first and if the addon is sufficient enough to fulfil the request before removing or marking the request as done.