Comment by Leeza Rana on How Can There be a Divorce When We Haven’t Even Married, Your Majesty? - Chapter 24

@Leeza Rana there might be multiple ones...
Since we don't know how many dukes there are and it isnt specifically mentioned that there are only 4 dukes (east,west,south, north)

@Leeza Rana   the kingdom he from is might be located in north that why he is Duke of north and emperor brother has land in north side in his kingdom that why he also thinking him as north duke