Nor am I, but live ball PF, dead ball PF...both are enforced.
Rule 14.9-- "If there has been a foul by either team during a down and there is a DBF by the other team in the action immediately after the end of the down, it is a double foul and all rules for enforcement apply"
The rule you quoted deals with a live ball foul by one team and a dead ball foul by the other team. That means the fouls will offset except for a couple of situations:
1.15 yard penalty vs. 5 yard only penalty and no change of possession on the play. The five yard penalty is disregarded and the 15 yard penalty is enforced from the previous spot (even on a scoring play).
2. If the dead ball foul is for delay of game for spiking the ball in the field of play, the offense can decline the penalty against it and have the delay of game enforced against them.
3. If the scoring team commits the dead ball penalty, the score counts, and the dead ball penalty is enforced on the kickoff.
The situation above would be a multiple foul situation and thus only one penalty can be enforced.