For all the NFL records Peyton Manning owns — and there are plenty — he is one victory away from the one accomplishment that eventually might define his legacy more than any other.If Manning’s Denver Broncos beat the Seattle Seahawks next weekend, he would become the first starting quarterback to win Super Bowl titles with two franchises.Manning is already a larger-than-life figure in Indianapolis, of course, widely credited with turning a basketball town into a football town by making the Colts truly matter. He led them to two NFL championship games, winning in 2007, losing in 2010.And now Manning, at the age of 37, two years removed from sitting out an entire season after a series of neck operations, has a chance to forever stamp himself as a figure of similar importance in Denver, too. As it is, he already has joined Craig Morton and Kurt Warner as the only QBs to lead two clubs to the Super Bowl, although they didn’t win with both.“If he can win this game, he definitely will be an icon in two cities,” said Morton, who was in Denver for six of his 18 NFL seasons.