No they didn't. The Socialist Party had candidates drop out of the race, so they wouldn't split the vote and hand the French Nationals a victory. This is well reported.
http://www.theguardian.com/commenti...-to-gain-power-but-its-defeat-is-only-partial
Not all of the Socialists dropped out, in the East region the National Front's Vice President to le Penn, Florian Philippot, lost big time to Philippe Richert, 47.6% to 36.6% while the Socialist picked up 15.8%. With the more than 20% surge in voting in the second round, the serious voters showed they don't vote for lunatics.