When you say "explicitly", do you mean you announce to the whole organization that this is your process? That in order for them to have something delivered they are required to request it twice? Are you actually telling people upfront that their first request will be effectively ignored? Or do you mean that you tell the org there's one version of the process but you are clear with yourself (and/or perhaps, your superiors) that you will actually carry out a second, undisclosed process.

Perhaps you're not filtering out requests on the basis of need, but on the ability of some individuals over others to figure out the unwritten rules and choose to play your game.