2 days vrata on ekadashi & maha-dwadashi
Ekadashi is accompanied by Vishnu-shrinkhal-yog. This is followed by Vijaya-mahadwadashi-vrata on the next day. Vrata to be held on both days by those who can. If one can't do vrata for 2 days, it can be done for only one day (only tomorrow), on Vijaya-Mahadwadashi.