Arguably, there is a distinct difference between the two episodes of the Royal Nonesuch and the impersonation of Peter Wilks. In the first case, the episode reveals the extent to which the villagers who are duped buy into their own duping and then seek to dupe others in turn. In the second case, the impersonation is much more savage and cruel, as it is the lives of Mary Jane and her remaining family, who are shown to be good people, that are being taken advantage of.
What is fascinating about the Royal Nonesuch is the way that the first audience, when they realise how they have been tricked, then go on to willingly trick their own neighbours because they don't want to be made fun of for having been fooled in the first place. Note what one of the audience says:
We are sold--mighty badly sold. But we don't want to be the laughing stock of this whole town, I reckon, and never hear the last of this thing as long as we live. No. What we want is to go out of here quiet, and talk this show up, and sell the rest of the town! Then we'll all be in the same boat.
The Royal Nonesuch therefore succeeds precisely because the audience play along with the trickery for their own purposes. The Duke and the King manage to successfully exploit man's own fear of appearing foolish and stupid to their own advantage. In many ways the villagers only get their just desserts in this sense. The impersonation of Peter Wilks, on the other hand, is very different, as it has definite victims and is much more a crime. Twain is very careful to build the character of Mary Jane to engage the reader's, and Huck's, sympathy for her, in order to show that this crime is far worse than the first.