Sonny replied without hesitation, “Of course. I like Dunc. Having one more dad is pretty good. Other people have one dad, while I have two. Isn’t that great?”
When Duncan first asked Sonny if he wanted a new father, Sonny answered that he already had one and was content with that.
Now that Sonny had grown up and developed a relationship with Duncan, he could accept having another dad.
Since he was more attached to Duncan, who was about to become his stepfather, he had grown distant from Hank.