Hello and welcome  I Like your post and well done with the images.
You stated that we point to the same layer in hypothesis 1/top image. Whenever we update one of the boxes, the other box is also updated, right?
Then in hypothesis 2: Every time you update the box, that’s the same as updating one of the boxes in hypothesis one - as they are connected. You say that in hypothesis 2, the update happens twice so there are double the amount of updates compared to hypothesis 1, right?
Just what came to mind