If you want to allow another user to login to a server with the same key as another user (which is terrible!), you should login as the user with the key you want to copy and run the below rsync command, replacing username with the username of the user you are copying the key too.
rsync --archive --chown=username:username ~/.ssh /home/username
Then afterwards try logging in to the server as that user, and you should be able to.
I'm a technology professional who's been passionate about computers since my Grandad introduced me to an Intel 386 back in the 90s when I was a kid. Those moments inspired a passion within for technology, and I've been playing around with anything with a circuit board ever since. Whenever I have a moment you can probably find me working on something computer-related, and this is where I like to write about those moments.
