If Angelique truly didn't want the duel between Barnabas and Jeremiah to happen, then why did she let it happen? With all that she had done and all that she could do, she could have found a way to stop it. Very likely she was having too much fun making Josette miserable to stop the duel.
Angelique still believes she can win Barnabas's love. Some process has gotten stuck in her mind, and she needs to be rebooted.
And Barnabas still believes that he has control of the situation. I understand his desire to protect Josette - but surely the simplest temporary solution would be to go away with Angelique, which Angelique wants, rather than to try to get Josette to go away.
It's good to see Millicent again.