Originally Posted by
gumbo999
This is not an exploit, if you queue up for both, once you get into one, the game will detect and not allow the other to pop while you're in it however it will keep your place in line. Once you finish either an instance or a bg the system will put you in front of the line which usually gives you an instant pop.
If you don't believe me try doing this at non peak hours queue for both bg and dungeon at the same time but queue as dps, enter to bg, even after it ends it will usually take a few minutes before dungeon pops.