Duplication (gender) – The ability to create a duplicate that is identical but has a different gender.
Ardina (Marvel) is the magically created female duplicate of Silver Surfer (The Order #4).
Linda the Duck is the female cloned duplicate of Howard the Duck. Shocket Raccoon is the female duplicate of Rocket Raccoon. Linda the Duck and Shocket Raccoon both first appear in Howard the Duck V6 #1.
Miss Sinister is the female duplicate of Mr. Sinister and first appears in X-Men Legacy #214.
She-Cat (Marvel) is the female clone of the White Tiger (Heroes for Hire #5).
In Superman #349, Superman returns from an interstellar mission to find that everyone on Earth is of the opposite sex.