Not again... Leave the poor deluded souls alone and let them maintain their completely baseless theory that the twins are somehow girls in the anime. I've tried before to show them the light, but alas, they denied it time and time again.
Just a bit of conjecture here, but couldn't it be that they were changed to girls in the anime so that any sexual implications between them and this "young master" were more acceptable to the average Japanese person? Sort of like many of the changes made to DBZ for its US release.
Japan doesn't seem particularly concerned about this sort of thing in anime, though (and there was very little going on between Oboro and the twins in the Utaware anime to begin with). They are certainly capable of making the change, but in this case there is absolutely no reason to believe they did.
In fact, I'd be more willing to believe they would actually play up the gay shota archer brothers angle, for the humor value.
And they did have a moment in the anime when they showed Doriy, Guraa, and Oboro, drunk, naked, and sharing a blanket, with the twins embracing Oboro from either side. Subtext? Naaaaah.