I know what you are saying to yourself, didn't you already have the Niners take a NT in round two? Yes, but there is a method to my madness.
Fun Fact: The Baltimore Ravens (where Vic Fangio was before joining Jim Harbaugh at Stanford) put a line together that looks like this Corey Redding DE 6'4" 292, Kelly Gregg NT 6'0" 320, Haloti Ngata DT 6'4" 350. They run what is really a hybrid of the 3-4, with only one true defensive end. This helps greatly in stopping the run and opens up holes for the linebackers.
If the Niners were to draft both Phil Taylor and Sione Fua (or is Tayloy is gone Powe) they would look like this: Justin Smith DE 6'4" 285, Sione Fua NT 6'2" 307+ (will add weight in NFL), Phil Taylor DT 6'3" 337. Ricky Jean Francois becomes the alternate at both positions.