This is rather easy to fix, and is JUST like the auto follow run off spam bug.

When you click to move with interact with target just make sure the mob has stopped moving before you send your alts at it. I always pull with my druid with key passing turned off, get mobs into position then unpause and go to town.
What happens is the click to move when the mob is moving targets a pixel in a higher quadrant like just a little in the air, and the game tries to send the toons to that location and they go running off almost like all the way around the world to get there.

The fix is patience and pay attention, get the mob standing still THEN click to move/interact with it.


Good luck!