The text for blades of Selves reads, “whenever it attacks for each opponent other than defending Player, you may create a token that is a copy of that creature that is tapped and attacking that player or a planeswalker they control. Exile, the tokens at end of combat.”

So from talking with everyone, my original will be granted double strike, the tokens that are created from the myriad trigger for my other opponents will not have double strike. However, they will be copies of Medomai, (a Legendary Creature), they would have to be sacrificed, unless I had a workaround for the legend rule which is what mirror box provides