Simple.
#1 SB III - Jets beat Colts (-17)
#2 SB XXXVI - Patriots beat Rams (-14)
Oddly enough, Giants over Patriots was only -11.5 I think. The perfect '72 Dolphins were acutally underdogs (-2 ) to the Redskins. Just goes to show you that being undefeated doesn't mean anything in the SB.