Material's color animation is linked across materials, but I don't want that

So I make a material (material A)
then I duplicate it (creating material B)
I animate color changes by keyframing the diffuse color - of material A.
Problem: Somehow material B is inheriting the changes I make to material A!
I see no reason for the two to be linked.

Goal: Let’s say I have a red cube and a blue sphere, and I want them to have the same material properties except that the color change keyframes are offset so that when cube=red sphere=blue, and when cube=blue sphere=red. Easy to visualize?

Thanks in advance for help/ideas.

I assume you use Cycles Materials.
Didi you make a copy by clicking on the number (in this case “2” in the image)?
That would give you an independant material.