'48 Leaf Wagner/Robinson - Print Variation?

[steve B]

Each color has its own plate.

removing stuff from a plate is easy, adding it to an existing plate is hard. (well, not hard if all you want is a line or to strengthen a small letter, you can just scratch that in. But adding shading is a new plate situation.

The colors would have been mixed by hand to get a particular shade that would reproduce the colors better. Black is pretty much always the same, but for one press run at least, they used the Magenta straight instead of mixing it to red.
Cyan was probably also used unmixed at one point. And yellow, but that's usually the first color printed, so it's the hardest to tell.

They were all on the same sheet as far as I know, so there should be differences on every card. I haven't counted, but I think I found maybe 1/4 of the different ones. At least three different main groups, plus some intermediate ones.