What is the ruling on the fast of one who experiences menstruation twice in Ramadan, for a total of 14 days of menses, meaning 7 days each time, and is she permitted to break her fast for 14 days?

The minimum period of purity between two menstrual cycles, according to the Hanbalis, is thirteen days, and according to the majority of scholars, it is fifteen days. If a woman menstruates for seven days, then becomes pure for ten days, and then blood returns, it is considered irregular bleeding (istihada), and the woman is treated as pure during this time.