Multiboxing vs Recruit a friend. Abuse?

I have noticed all of a sudden a huge amount of Multi-boxers showing up (players that use several simultaneous accounts). I have seen a bunch of ppl get to lvl 60 in just a day (~12 hours) with all 5 or whatever characters.

Is there some kind of exploit or adding of multiple referral bonuses that would cause this?

What is going on? ppl almost capping in a day seems a little silly to me when the previous records are ~4days.

Is there something here that needs to be investigated maybe?