Hi,
Welcome to the ehealthforum. I am glad to help you out. Sometimes periods can come twice a month in a cycle that is short, with one period coming in the first 4-5 days of the month and the second period starting in the month end.
If you have short cycles of 24-26 days, then one period can start at beginning and other at the end. However if it happens again then it can be due to polymenorrhea which could be due to several causes such fibroids, adenomyosis, endometriosis, uterine polyps, hormonal imbalance, thyroid problems and bleeding disorders.
In that case, consultation of a gynecologist is required.
It is very difficult to precisely confirm a diagnosis without examination and investigations, and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.