I just leveled the shaman to 70 about 3 weeks ago. I have another group that's 70 - pally, 2xmages, 1xshaman, 1xpriest - but it's a lot less noticeable that they are multi-boxers - different names and classes. They are about 8 months old. In all the time in the battlegrounds I've never come across another boxer. I've seen a couple people with similar names - but they turned out to be friends or father/son. I've also had a few people tell me they MB - but they weren't on their MB accounts.

Xbox - the 5 shaman team is on my server - although I've never seen him on - and I have been on the server since wow started.

P.S. Now that I think about it - I did see a guy leveling mages in SM - but only saw him once - never a 70 MBer.