In case you want to do some pair programming it's possible to do this using Nomachine NX and it's ability to share sessions.

Please note that both sessions must be shared on the very same front node! Make sure to agree which node both users are going to use.

1. Connecting to other user's session if you haven't started any session yet

In this case, make sure to skip the step of creating your own session and simply choose the session you want to connect to

2. Connecting to other user's session if you have your own sessions running at Gateway