I am not clear on what would happen in the case where you try to login with an account and password using a different nickname. Aren't these tied to a specific, registered nickname?

What would happen if you connected with your registered nickname, logged into it using SASL and then, as with your situation, connected a second client, failed to login because the nickname was in use, used a second nickname, and then used an account and password connected to the first nickname?

Would the IRC server disconnect your first connection and change your second connection to use your registered nickname?

Do all IRC networks handle this in the same way?