Steam added a P2P caching mechanism recently and allows downloading games for other local machines that already have the game installed. Greatly helps with avoiding duplicate downloads on a steam deck, for example.
I also added a similar mechanism to my own product years ago. Works flawlessly. Using content based addressing already made it quite easy to implement.
I also added a similar mechanism to my own product years ago. Works flawlessly. Using content based addressing already made it quite easy to implement.