Dual engine oil filler ports

I understand that Cummins bought Onan. Also understand that Cummins and Kukje, builder of the Branson tractor, partnered in building the A series of engines for use in Branson tractors..

I have a 2016 Branson 2400 and just discovered a second what looks to be a fill port on my A1100NA 24 hp 3 cyl engine. The first one is atop the valve cover where one would expect to find it. But an identical rubber/silicon/orange plug is atop a bulge in the side of the engine block (casting)to which the injector pump is bolted (mounted) . Pulling the plug and looking down into the cavity, you are looking down directly at the top of the injector pump drive gear and it seems to be a clear shot to the engine oil sump.

Nowhere in my published data received with the engine (user and chassis service) is the function of the lower port mentioned. I assumed it would be an oil fill port for locations where the upper fill port is unaccessible.

Knowing what I just found out about with Onan (surfing the www and here in YT, 2005 posting, this forum), and knowing that Kukje-Cummins were using the Onan original designs as an aid in developing the A series of engine Kukje-Cummins engines, I can speculate that it's a carryover from Onan power equipments used in motor homes and things of the sort where access to the top of the valve cover for oil filling is not practical so a lower level fill port was added......what else could it be? Not Front end oil, not trans hyd oil, I know where those fill ports are and there aren't any more oil sumps in the tractor.

Thanks for any time spent on this, including thoughtful speculation.

Many, many engines over the years have had more than one crankcase oil fill port location, I wouldn't stress too much about it.

Probably an engine intended to be sold to others for many uses. I have a little Yanmar that has at least three oil fill locations. Only one used in my JD, but that basic engine was used in tractors, excavators, refrigeration units, skid loaders and I'm sure many others by several machinery makers, not just JD.

Cheaper to make one universal engine block casting and one universal valve cover.
More often the block will not be fully machined if the application does not need it.

I had a 25 hp Kohler that had three,one on each valve cover and one for the dipstick tube.

Thanks for the inputs guys. Been away from the site for a few days and checking back in this AM.