I’ve seen older sumps with a steel baffle attached with fasteners similar to those that attach the data plate. Later ones like mine (that I know ro have come from an O-300D) has the baffle cast in. I’ve always assumed that the purpose is to smoothly divide the flow from the carburetor equally to the left and left intake manifolds. Quite a few years ago
I posted pictures of a steel one still installed, and a mangled steel one that a friend found lodged in an intake valve seat

. I thought I had a photo of my sump with the cast-in-place flow divider but I didn’t find it.