Editing Keyframes IFFY

I have a series of objects. I edit the keyframes for visibility of object-1. All ok. Object-2 All ok. Object 3 + Any edit to ONE keyframe CHANGES ALL KEYFRAMES FOR THIS OBJECT. Same for Object-4, Object-5, Object-6 …

Is there a hidden setting (not represented in the EDIT KEYFRAMES Dialog that changes editing to ALL keyframes for an object ?

-C.

Any change that you could send us the model and include steps on how to reproduce this?