$allusers = [ sort { $a->{'user'} cmp $b->{'user'} } @$allusers ];
            
my ($temp, $grouped);
my $ctr = -1; 

for ( @{ $allusers } ) {
   if ( $temp && $temp eq $_->{'user'} ) {
      $grouped->[$ctr]{'amount'}    += $_->{'amount'};
      $grouped->[$ctr]{'duration'}  += $_->{'duration'};
   } else {
      $ctr++;
      $temp = $grouped->[$ctr]{'user'} = $_->{'user'};
      $grouped->[$ctr]{'amount'}       = $_->{'amount'};
      $grouped->[$ctr]{'duration'}     = $_->{'duration'};
      
   }
}