Is it permitted to marry two sisters?

Answer From The Annual Reading Schedule - Week 7 Notes For Genesis: No. Although Ya'aqov (Jacob) married both Le'ah (Leah) and Rachel he did not set his heart out to do this but rather was deceived into it. Leviticus 18:18 prohibits taking a woman as a rival to her sister. It is clear that Le'ah was very sad and had inner-turmoil from the rivalry between her and her sister Rachel. I do not believe Yahweh wants any woman to go through that with her own flesh and blood sister. A woman could become a rival even if not a sister, but it is probably inevitable and even worse in a situation with two sisters and therefore probably the reason it is prohibited.