I saw someone running 4 sham's in AB a month or so ago. All similar names, player movement really made it obvious, as did simo-casting chain-lightning and totems. They all looked to be elemental spec. All already had full suits of lvl 70 BG gear from what I could tell. They appeared to have it down very well. I didn't watch a whole lot, I was busy attacking other nodes.

...

I've seen dual/triple hunters in WSG a time or two. Ice traps... ice traps... ice traps... multiple pet charges/stuns... and by keeping the hunters somewhat spread out, the attackers never seemed to find their 'dead spots' (too close for range/too far for melee).
I did activate a 3rd account to try this for myself very recently... and it worked as well as advertised. I did die a few times, but that was my fault for simply not having keys bound correctly and, in general, for being too excited and stupid in the heat of the moment.