Is there any difference in two gender fields in profile editor (one below the birth date and another one - above real name)? Maybe one of them is intended to reflect my role-playing alter ego gender, I don't know

I've never noticed that, then again I don't spend much time looking at my profile. I changed the top field to female, which resulted in my profile reflecting that I'm a girl with a shiny bald head and a beard, quite disturbing if nothing else. I corrected it and then changed the bottom field which did not result in any immediately noticeable changes. So I guess use the top field if you want your gender known.