Ask your engineer about two columns of fluid in the same manifold at different pressures please.
The assumption that what pressure you see on the gauge is what’s in the manifold (gallery) and it damn sure isn’t.
Whichever feed has the least amount of restriction will try to overcome the other.
Ive never seen anyone front and rear feed a block. That would be redundant, which is what happened to me when I pulled the plugs out of the main feeds. I had oil coming in from the bottom and in from the main oil gallery and you couldn’t a rod bearing in it. At times it will be easier for the oil to NOT go to the bearings and back up another route.
Running two fluid columns is bad IMHO.