Maybe he should ask for a Siamese Twins Token, so he can stare at both ?
Genes don't work like that...
I'm sure we'll have a Bynar race unlock at some point, though. Eventually there'll be no other races left to add to the C-store and there'll be money in it, so it is all but inevitable. You get a captain who comes with a sixth Away team member, but if either of you dies, so the does the other. I don't think they have to be genetically identical, so both kinds of butts would be an option.
But you'll have to play rock paper scissors every time to determine who gets the captain's chair.
City of Heroes has an interesting microtransaction item that allows you to have complete freedom in the tailor. Without this item your build and gender are fixed at the moment of character creation, but with the item, you are allowed to create Bruce Banner/Hulk and Ranma. Might be roleplaying a shapeshifter that changes gender. There are numerous shapechangers in Star Trek, the prison girl in Star Trek 6, Q, changelings, and I am probably forgetting a few. So there is an IP reason to have more flexible options for aliens.