As a Demon Hunter, if you place multiple Caltrops with Jagged Spikes rune on the same spot, does the damage of each one stack? Or does the monster just receive the 45% weapon damage during the trap lifetime?
I haven't actually tested this specific combination, but it should work the same way as Spike Trap, eg. if you place down 10 Caltrops on the same spot as soon as a monster enters that area then they should get hit by 10x 45% weapon damage, or a bit less than 2 Spike Traps worth of damage. For what it is, it probably isn't an efficient use of your discipline, though it should stack just fine.