using one authorized_keys file to another account

[Tapas Mishra]

I have an access to a machine on lan via ssh and I am  using key based
authentication on it.
I created one more account on the remote machine and copied


cp home/oldaccount/.ssh/authorized_keys
home/newaccount/.ssh/authorized_keys

Now when I tried to login to the other account via ssh from my laptop
it did not worked.
Though the copy of keys from laptop .ssh/id_rsa.pub to
remote machine new account .ssh/authorized keys did worked.

I was wondering I had added same keys to old account so why did simple
copying the authorized keys from one account to another did not
worked.
Because when I did cat id_rsa.pub > authorized_keys in new account I
had created same file which was in old account.
Why is this happening or my observation is wrong.