Ok so this happened when me and my friend, 70 rogue and 70 mage, were farming strat for the mount from Baron Rivendare.
My friend entered the instance before me and recieved the barons ultimatum. When i entered i noticed that i did not have the ultimatum. However the instance went smoothly and due to me having leather over his cloth, i am the one who engages Baron 1st. When he died i recieved 100rep for the non ultimatum kill, but also the 300 from my friend having the ultimatum.
Pretty useless at 70, but lower levels might be able to play with this for extra rep.
If this is a repost, I grovel in your flames