iX, Ikksu, Irregular X, al = "X" with different writing. Ikksu, =/= Ekksu (Rockman X)
hence his name is actually also X. to the english reader there is no difference. to the japanese reader, they clearly see the difference, as if I spelled Flame as Fleym.
also, RX is Return Ikksu. cuz he's, well, Ikksu returned. >_>;