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. If you had a period say on the 2nd of a month, then in a 28 day cycle too, the period can come on 30th of the same month. However, this would mean that it will happen once 2-3 months and not every month.