Reference: Fataawa Ramadhaan – Volume 2, Page 608, Fatwa No.601
Fiqh al-‘Ibaadaat – Page 198
Question: If one was to have sexual intercourse a number of times during the same day in Ramadhaan, is he/she then required to pay the penalty (kaffaarah) the same number of times?
Response: That which is understood from the madh.hab of Imaam Ahmad is that if one has sexual intercourse a number of times during the [same] day [in Ramadhaan] then a single penalty (kaffaarah) is sufficient. However, if this occurred a number of times over two days [or more], then he is required to pay a penalty (kaffaarah) for each day because each day [of fasting] is separate [from the other].