Any pups that we've ever had (labs) we've always fed the pups 3x a day instead of 2x until they were at least a year.  You may not be feeding them enough is my first thought.  Second thought is we make them wait until we put the food in front of them and tell them it's okay to eat.  I also make sure that I am able to grab their food bowl at any time while they are eating and any sign of aggression gets reprimanded and taken care of immediately.  Is it a free for all at feeding time or is each fed individually?  If it's a free for all start feeding the pups separate and in their own dishes and once one or both are done take the bowls away and remove the dog from the feeding area.