Akroma should be legendary - it is in MtG, and named cards should all be so. Additionally, play balance with two of them in a deck is a problem.
I think it's an oversight... make Akroma legendary like other MtG 'legends.'
Yeah, if your opponent had 2, then they got a 2nd through a means of drafting a legendary, or the land that has a chance to give you a legendary creature.
Akroma is legendary in spellslingers already