Is this a Cheat or Hack?

whilst playing in EOTS, i was hanging around the Mage Tower doing my defending duty (yes it's possible for an Alliance player to defend!) a Shaman rolled up and threw down an alarming amount of totems, maybe I'd been playing too long or had too much Beer i thought and were seeing things.

But then i saw another shaman EXACTLY the same as the 1st one I'd seen, same gear, exacly the same movements & really difficult to seperate as the 1st, on top of each other almost.

Before i could say "..wtf" i was killed by 2 lightning bolts, now seeing as I'm a protection warrior with 15k hp i thought his was unusual, anyway i ressed and ran back up and BAM! dead again by another 2 lightning bolts!

so i moused over this Shaman and i saw not two but THREE identical shamans, and when i say identical i mean exact! all doing the exact same thing, i checked my combat log and noticed they had 3 every so slightly different names (1 different character) and i was hit not by 2 lightning bolts but in fact 6!
I checked the scoreboard and these 3 shamans were sure enough taking up 3 player spots too.

how is this possible? is this cheating? or maybe it's accepted by Blizzard as they're 3 different (i assume) payng accounts?

anyone who can put me in the picture here please?