Yeah I get what you're saying but there's a false correlation between birth sex and gender identity. These are not necessarily aligned (though for the majority of us they are.)
So this is not even slightly like 2 guys with a penis, this is 1 guy + 1 girl (with non-standard equipment.)
I understand that the false correlation is not of your making, but of a monotheist, absolutist cultural tradition. But just because it has very deep roots doesn't make it any less false.:shrug