my $output = [];
foreach my $hash (@$data) {
  my $cust_id = $hash->{cust_id};
  foreach my $id (split ",", $order_data->{$cust_id}->{order_ids}) {
     $hash->{order_id} = $id;
     print Dumper $hash; # outputting here yields perfect data
     push @$output, $hash;
  }
}
print Dumper $output; # outputting here gives trashed data