Muhammad ibn al-Hasan commented: "There is no contradiction between these narrations. My conclusion for reconciling them is that if a woman becomes pure after midday (Zawal) and before four feet of shadow have passed, she must make up both Dhuhr and 'Asr prayers. However, if she becomes pure after four feet of shadow have passed, she is obligated to make up only the 'Asr prayer. It is recommended for her to make up the Dhuhr prayer if her purification occurred before sunset. This explanation eliminates any contradiction between the narrations."
Commentary #2