Septate hymen is rare, and occurs when people are born with extra tissue on their hymen, which is a thin tissue that is around the vaginal opening. As a result, those with septate hymen may have what looks like two vaginal openings. Depending on the situation, some with this condition can find it harder to insert a tampon during menstruation or have painful sexual intercourse. If you are concerned that you have a septate hymen, the only way to know for sure is to see a doctor, specifically an OB/GYN. They can perform a small surgery called a hymenectomy which can remove the extra tissue on your hymen to make one vaginal opening. This surgery does not have long-term complications.
You can learn more about septate hymen here.