Use multiple SSH private keys on a client
How to configure multiple ssh keys
To use multiple shh private keys on a client you need to create the file config inside the folder .ssh and use the following entries:
Host myshortname realname.example.com
HostName realname.example.com
IdentityFile ~/.ssh/realname_rsa
User remoteusername
Host myother realname2.example.org
HostName realname2.example.org
IdentityFile ~/.ssh/realname2_rsa
User remoteusername
where IdentityFile is the private key for realname.