If you find an NPC that doesn't move (they stand in the same spot day and night) 
you can clone them and their equipment. First, you need to get an item that does 
damage over time before you can do this.

1.Go up to the NPC and drop the DOT item near the NPC.
2.Wait for them to walk over, pick it up and equip it, thus they start taking the
  damage.
3.Once they die, loot their items from them.
4.Resurect the NPC.
5.Walk a couple screens away and advance time one day.
6.Go back to the NPC and they should be cloned.

Note: You have to drop the item right beside most NPCs or they will walk back to
their starting spot. Also note that some NPCs won't equip certain items and armor 
is size dependant.