bs"d If one asks a question of one Rav they’re not supposed to ask another Rav the same question. Does this apply also for when a woman asks a Rabbanit/Rebbetzin a certain question? Thank you.

Shalom, Thank you for your question. The laws of asking a halachic question of a rabbi after having already asked another rabbi for his ruling are quite complex – but in general you are correct that many times it is forbidden to get a "second opinon". For example if you asked a rabbi if a food you cooked was kosher and he ruled it is not kosher, it is forbidden to ask a second rabbi. (Though there are many types of questions, and many ways of asking, that allow asking a second rabbi.) In relation to asking a woman – no matter what her status is, be it a Rabbanit (the rabbis' wife), or any learned woman – the laws are just the same. Women are allowed to give halachic decisions just as men do. The only proviso is that they have studies the halacha and are well versed in the law. So, if you got a halachic ruling from a woman you are bound by it and may not ask for a different ruling, be it from another woman or man. Blessings.