Baby names????

I'm preggo with baby #4 and hubby and I have been disagreed on one thing, if it's a boy what would be his name. Hubby wants to name the baby after him, but we already have a son who is not name after him. Can the second child be a jr? I'm kinda confuse?  In my opinion first born sons are suppose to carry the jr name, not the second son. Correct me if I'm wrong.