Lets say that one was able to create multiple Stalking Vengeance . After one of that player's creatures is killed, would that creature deal damage equal to it's power for each stalking vengeance in play?
If you control more than one Stalking Vengeance and a creature you control dies, each such Stalking Vengeance's triggered ability will trigger (except that if that creature is a Stalking Vengeance, its own triggered ability won't trigger this way), and those abilities will go on the stack the next time a player would get priority (C.R. 603.2, 603.3). As those abilities go on the stack, you choose separately, for each one, which player or planeswalker it targets (C.R. 108.1, 603.3d, 601.2c, 114.1d).
Multiple stalking vengence