This is easy. Before Hodgdon took over Winchester powders, The H110 and WW296 were different powders. the data is probably based on older powder.
No, not really. Hodgdon has always contracted the H110, HP38, etc. from Winchester.
The part of Olin Corp/Winchester that originally produced ball powders, licensed many of their ball powders to Hodgdon while they still sold their own WIN versions but allowed Hodgdon to call them something different.
Back in 1970 or so they (Olin/WIN) opened a plant in FL called St Marks where the process is specifically ball powders, and much later on licensed the WIN marketing to Hodgdon all together. When I last knew anything I believe that St Marks was being operated by General Dynamics for something like 25 years now, but I am retired so it is not my job to know these things any more.
So in a way, since about 1970 Winchester Powder and Hodgdon ball powders are really just repackaged St Marks powders since neither the current incarnation of Winchester operates a powder plant, and Hodgdon never has been a producer.
So, those WIN ball powders from St Marks that Hodgdon sells have always been the identical powder and often from the same batch, but could have also been from different serial runs, which explains the slight differences from batch to batch.
Some lawyer somewhere could probably ply me with enough Scotch to explain why companies like Hodgdon feel the need to "repackage" and rename powders differently from where they originate, but it would require Macallan 18 from single Spanish Sherry Oak casks, not the cheap stuff........ It never made sense to me and never will.
HP38 and H110, have always been W231 and W296 respectively for example, and why they felt the need to call these or the others by different labels with their own names is a mystery to me.