Well, i dont know how, but a friend of mine is playing an elemental shaman, duel wielding and both flametongue weapon on both weapons and it works! I mean he gains 2 x flametongue weapon spl dmg. (He's still a noob shammy who just reached 80 but i've seen with my own eyes in a net cafe) Now most of us knows the good old trick to use duel wield ( Respec enc - wield both weapons - go back to ele), but this way, you dont get benefit by applying flametongue weapon on off-hand weapon.
He reached 80 2-3 days ago and i though it was a bug and will be fixed when he reached 80 but it still works.He's also not aware how did this happened, what he told me was, he was lvling as enc, then he respecced into ele while duel-wielding and both weapon were enchanted with windfury.( he doesn't have duel-spec, also changing the off-hand weapon does not brake the bug) And no, it didn't work on me:S
Is he just a lucky bastard or is there actually a way to do this?