Why are the king and the duke fighting? Why do they get back together?

Their big fight actually happens in Chapter 30. On the raft, the King and Duke get into an argument about the money and start accusing each other of stealing the cash and hiding it, especially since they had added the proceeds of the Royal Nonesuch to the pot. The Duke finally physically attacks the King and forces him say that he took the money. Next, both men get drunk and make up. You can check this out at,

http://www.gradesaver.com/the-adventures-of-huckleberry-finn/study-guide/section6/