Here's a partial hierarchy of my current Blender scene:
Armature \--Mesh 1 (parented to a bone) \--Bezier 1 \--Bezier 2 \--Bezier 3
Bezier 2 and 3 were "Duplicate Linked" from Bezier 1, so they all share the same curve data, but I'm not sure whether that has anything to do with the issue.
Anyway, what happens is, I rotate Bezier 1, and then set a keyframe on that rotation. It appears to work fine at first. But then when I change frames, suddenly I see the entire armature rotate to some weird angle. Then, when I click on the armature, I see a keyframe on its (object-level) rotation as well, which I never set. I can remove the armature keyframe and put the rotation back to zero, but then it removes the keyframe from Bezier 1 as well.
I don't want to share the .blend file just yet, but I do have a copy saved at this point for when I do in the future. In the meantime though, is anyone aware of anything that could potentially cause this behavior? Or can it only be a bug in Blender?