Duncan couldn't marry.
I remember in the show Duncan was never married he said so. Some gypsy lady told him that he would never ever marry and when he proposed to Tessa she got killed. So having him be married to Kate was lame and just freakishly obvious to anyone that's watched the show...also, I didn't catch how Kate was still alive at the end of the show, I thought that guy killed her when he killed all of his other thugs.
Cake or death?