Would a separate NPC just for this really be necessary? The issue started with the Armoire, can't it end there? When trying to store a duplicate item that cannot be otherwise discarded, have one of those "click the confirm box and then click ok so we know you really mean it" windows pop up asking if we'd like to overwrite one with the other. Two sets of AF go into the Armoire - one remains to be taken out later. Just throwing ideas out there; this was my first impression of a quick fix.