wow, i like how you don't know what you're talking about!!
lemme see if i can do a better job at explaining
sora duel wields when he fuses with goofy in valor form, the reason for
his duel wielding is because goofy's heart is strong like sora's, and since sora's
the keyblade wielder, two hearts, two keyblades, he can also duel wield in final
and master form, based on the same principle, Roxas can duel wield on the basis
that he's sora's nobodie and since he is part of sora, he can call the keyblade,
because his hart is the same as sora's he duel wields because he is part of sora's
light (oath keeper) and dark (oblivian)