How do i copy a layer with a motion tween without linking the layers?

[#1]

How do i copy a layer with a motion tween without linking the symbols in the layers and the layers itself?

For example if a have a symbol and i make it into a motion tween and then i copy the layer and paste it to make a copy of the exact same motion and layer. But then when i change something in one of the layers they both change and I don't want that. I just want to copy a layer so that I don't have to make the exact same motion again.. Somehow the pasted layer automatically links to the other layer that i copied. How do i unlink these layers?

Appreciate your help! 🙂 

[#2]

i don't know how you linked them.  just use copy layer, then paste layer and then edit the layer you want to change.  the unedited layer remains unchanged.  

because you must be doing something (not obvious to me) to cause the issue, lock the layer you don't want to change.  then edit the layer you want to change.