2 different SSH connections on 2 different port

I need to configure 2 SSH connection on my server : one on port 22 and the other on port 422.
Each connection must be linked with a different LDAP server.
I think this can be done by creating a new SSHD service with a different config file (sshd_config2), linked with a new PAM entry in /etc/pam.d/
Have you anything more easy to achieve that ?
Thanks