Play Minecraft with the same account in the LAN?

I and a friend want to have Minecraft Java together on the LAN but he doesn't have his own account and that's why he plays with mine. Is there any way to play it in the LAN with the same account.

If you are in lan you can simply log out then it should also work without an account

No. An account can only be online once on a server.

As soon as someone else logs in with the account, the session starts on your device.

But if we play together in the lan would it work somehow?

But you have to register to get into Minecraft

It really works that way for me