In ~/.ssh/config
you can specify host aliases. For example, let's say you have two different keys you want to use for the same user living on the same host. You would do that in the following manner... (excerpt from ~/.ssh/config
)
Host localhost
User git
IdentityFile /home/systems/.ssh/id_rsa
Host myaliashost
HostName localhost
User git
IdentityFile /home/systems/.ssh/another_id_rsa