Cannot move keyframes added in the material Node Editor

I am making an animation of a sheet of paper moving through a printing press. Gradually color is added to it, which I did by adding keyframes to show/hide different textures in the Node Editor (using the FAC setting in the mix shader of the material). That works very nicely.

Unfortunately multiple sheets must go through the press simultaneously, one after the other. I assumed I could copy the paper mesh, making sure its animation is unlinked and then simply move the keyframes to have a second sheet go though the press 2 seconds later.

That works fine for the keyframes that determine the starting position and end position of the paper moving through the press. I cannot however move the keyframes from the Node Editor that switch between textures. If I do that, those keyframes also shift for the original paper mesh. Is there a way to move Node Editor keyframes of a copied mesh, without affecting the original object?

Sounds like the problem is that the material is shared between the sheets of paper, so when you keyframe parameters, it’s changing all of them.

Too early in the day for me to find a neat solution, but you’ll definitely need to start by duplicating those materials.