This sounds like a job for OO. Build two indecies of people objects, one by id and the other by name. Of course, both indecies are hashes where the value is a reference to the correct person object. Then give your object get methods:

result:

{
  package Person;

  sub new 
  {
    my $proto = shift;
    my $class = ref($proto) || $proto;
    my $self  = {};
    bless ($self, $class);
  
    # Add member variables.
    $self->{Name}         = @_ ? shift : die "Person Constructor expec
+ted a name";
    $self->{Rank}         = @_ ? shift : die "Person Constructor expec
+ted a rank";
    $self->{SerialNumber} = @_ ? shift : die "Person Constructor expec
+ted a serial number";
  
    return $self;
  }

  sub Name
  {
    my $self = shift;
    return $self->{Name};
  }

  sub SerialNum
  {
    my $self = shift;
    return $self->{SerialNumber};
  }
  
  # And whatever other methods you want.
}

my $dad = Person->new( 'dad', 'top dog', 1 );

my %ByName;
while( ReadPeopleDataFromSomewhere() )
{
    my $person = Person->new( $name, $rank, $serial );
    
    # Error check for repeat names? 
    # I didn't, but that might not be a bad idea.
    $ByName{$person->Name()} = $person;

    # Likewise, one hopes that serial numbers are unique.
    $BySerial{$person->SerialNum()} = $person;
}
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The above sample code is untested but gives you the idea. You should definately read perltoot.