Support generic hardware objects/placeholders which can be placed multiple times in the racks

Objects like cable ducts, fillers, maybe even patch panels and KVM switches need to be added to the racks for proper hardware organization and rack display, but in many cases (like cable ducts ecc., we have dozens of them :-) it doesn't make any sense to keep them as separate inventory objects in GLPI.  It would be nice to have some kind of "generic hardware object" or "placeholder" which can be placed as many times as required in a rack.  I don't think this is currently possible.