NEW YORK — Two games against so-so, at-best teams are far from a defining body of work. However, James Harden’s effect on the 76ers is undeniable. The point guard recorded a triple-double to lead the Sixers to a 125-109 victory over the New York Knicks in Sunday’s matinee at Madison Square Garden. This comes after Harden’s stellar double-double in his Sixers debut in Saturday’s road victory at the Minnesota Timberwolves. This time, Harden had 29 points, 16 assists, and 10 rebounds to go with five steals. Just like on Friday, the Sixers (37-23) also received stellar performances from Joel Embii…