Thanks for the pointer to the application notes. Really helps me understand the results I see.
Well, except that as a direct consequence of the hypothesis made in this application note,
That first point is worth stating again: All emulsions have the same intrinsic contrast - the same
range of illumination that takes them from white to their DMax. There is a common
misconception that the paper is made from a blue sensitive high contrast emulsion and low
contrast green sensitive emulsion - this is not the case.
there should be a bump in the middle of the D-versus-log(exp) curve (see the graphs there). And what you see is a dip, consistent with the superposition of two emulsions, one soft, one hard.