If you got your period twice in one month, you may have had a short cycle. A menstrual cycle can be as short as 23 days and some women experience this when they are nearing menopause. However, you may not have gotten your period twice in one month at all. Some women experience mid-cycle bleeding they believe is a period, but is really not. If a woman is on hormonal birth control, she may also experience breakthrough bleeding, which is not an actual period. Also, polyps and fibroids can produce vaginal bleeding that is not a true menstrual period.