No, they can never exchange electicity directly. They did not know each other! For indepenend use at one phase with different energy plan: this should be possible, i think so.
For cluster use: The "cluster" Symbol in the app does control both Hypers with the same settings 50/50 usage. If one hyper is empty first, the second Hyper will deliver more electricity to grid.
For independant usage: if you use CT mode at one hyper, then you can "send" by hand electricity from the second hyper to the CT mode ones, if you feed more power than your house grid needs. But you loose 50W to the grid, because CT mode will start AC loading above a 50W tolerance limit, only. And conversion loss, two times of 20W, so this is not a desired usage for two Hypers from my point of view.