Have the Duke and Duchess been discovered in the ending of blackmail?

The Duke and Duchess were discovered.

Finally, let’s talk about why Arnold finally appeared here. Arnold, who came out of the police station, had a grudge against Dave and wanted to seek revenge from Dave, but Dave lured him with money and asked Arnold to wait for him at home. However, instead of waiting for Dave, he was shot by Ranjit.

The movie "The Duchess", shot based on Georgiana, ends with Georgiana living happily at Chatsworth Manor with the Duke, mistress, and children until Georgiana's death and the mistress takes over.