Can ssh listen on more than one port?

The answer is yes.

If you're using OpenSSH server, all you would need to do to make the SSH server listen on more than one port is to edit your sshd_config file and add additional port entries.

The sshd_config file can be found at /etc/ssh/sshd_config on my Debian server.

And in it, there is a section which says:

# What ports, IPs and protocols we listen for
Port 22

The SSH server can be made to listen on additional ports by adding them to the file.

For example, if I want my SSH server to listen on ports 23 and 443 in addition to Port 22, I would edit the relevant section in my sshd_config file so it reads:

# What ports, IPs and protocols we listen for
Port 22
Port 23
Port 443

And finally, to activate the changes, the SSH service needs to be restarted. 

On Debian, the service can be restarted by running:

service ssh restart