my @l=( {FN=>'Les',LN=>'Howard'},
        {FN=>'Larry',LN=>'Wall'},
        {FN=>'Randal',LN=>'Schwartz'});

foreach(sort {$$a{LN} cmp $$b{LN} or $$a{FN} cmp $$b{FN}} @l){
  print "$$_{LN}, $$_{FN}\n";
}