I recommend no duels at all. We have no guarantee that they will prove anything and it's far more likely that it will just result in one fewer townie voting during the day. With this insistence on dueling, the remaining scum could continue to refrain from killing at night and still keep whittling us down. Better to duel no one, lynch CA twice, and block CB during the nights until CA is dealt with and we can spare a lynch for him.