I first started dual boxing with two computers and usually just doing a high-low powerleveling thing. I noticed that I would DC in instances while following ALL THE TIME. It was annoying as hell. So basically, I'd just sit back without moving and let the mage AOE grind out an area and then move up. A real pain, but it made the pulls easier without the lowbie pulling aggro. Still, I never noticed it any other time except instances and I really wanted a fix.