MrSharkbaitClassy indeed and, really good value here. No, the Sonnets don't have the same nib as the Duofold. It is smaller and doesn't have the dual colour heart shape. In my eperience, the Sonnet is slightly springier (and less refined) than the Duofold which is intentionally a very rigid nib (for writing on those old multi copy carbon papers). Both good - just different.
MrSharkbaitMarlowe7 is correct ... the Sonnet nib is different from Duofold. However, the people, skills, tools and equipment used to make them are essentially identical (for the 18k nibs).