33a bottom
The gemoro tries to prove from oson, that chovel pays momon not malkus. Since we see you have hasrooh, and the lady did not die, so there is no chiyuv misah only a chiyuv of malkus of chovel and still the torah says "pay for the vlodos" so obviously momon comes first.
But here you pay momon to the father of the fetus, and you are chayav malkus for the woman who you hit. That's 2 sperate people, so who says you don't get both. (Only reb ashi, on the top line of 31a said that 2 different people is still pottur for kom ley bideraboh, and that's by misah and momon who says it's the same by malkus and momon?)
Avrumi Hersh, London england
Shalom R' Hersh!
The source to exempt a person from both paying money and incurring lashes is the verse in Devarim 25:2 which says lashes are given "Kedei Rish'aso." It teaches us that apart from the prescribed Malkus, there is no other punishment for the same sinful action, such as monetary payment. This apparently is regardless of whether there were two separate victims or not.
This interpretation will become more clear later in Kesuvos 37a. Still, it may also be helpful to see where Chazal speak about this on other Dapim. For example, in Kesuvos 32b (with Rashi there, end of 31b, DH v'Kaima Lan d'Ein Lokeh u'Meshalem), Yerushalmi Kesuvos 3:1, and also Makos 4b.
Regarding Misah and Mamon, in particular Rav Ashi's view, I understand that you are citing Rashi's explanation on the top of 31a. A further discussion of this issue -- with dissenting opinions -- can be found in the Tosfos beginning on the bottom of 30b (DH Rav).
I hope this helps!
Best wishes,
Yishai Rasowsky