My friend was playing around on his shaman earlier today when he came across this.
He summoned out his earth elemental while soloing Problim in Tol Barad and he noticed that his fire elemental didnt get the usual 2 minutes cooldown. He then tried to summon out the fire elemental and they were both out at the same time and both worked. He have done this several times after.
Ill try and get a picture of it on here once I figure out how to.
As you can see both elements are out at the same time.