In my recent video, I used 2 GridWarp nodes to create a stage curtain opening effect.
I got a comment today asking if it's possible to copy and paste to reuse the keyframes from one side to the other side.
I don't think we can use the keyframe reverse on a GridWarp node to achive what we are trying to do, but there is another way to get this work.
As you see in following screenshot, we first add a transform node to the right side, flip the image:
Copy and paste an instance of the left side GridWarp1 after the transform node, and add another transform node after, and flip back the image: 
Now, we can continue adjusting the lgridwarp keyframes and curves, the changes will be automatically be applied to both sides of the curtain animation, because we use an instance of the leftside GridWarp node.
As we will need to focus only on one side animation, this will save us a great amount to time making this curtain opening effect.
Thanks to Yuna l 유나티다 for this great question!
Essential Video Editing