%data = (
  serial_number => {
    A => 0 or 1,
    B => 0 or 1,
    # etc.
    order_stamp => number
  },
  # etc.
);

##</code><code>##

  @serial_order = reverse sort { $data{$a}{order_stamp} <=> $data{$b}{order_stamp} } keys %data;