If you slurp the file into a string you can use a regular expression look-ahead to make sure the file contains "First Name" and "Last Name" in the right order.

use strict;
use warnings;

my $fileText;
do {local $/; $fileText = <DATA>};

my $rxOK = qr
   {(?xms)
      ^First\sName
      (?=.*?^Last\sName)
   };

print
   $fileText =~ $rxOK
   ? qq{File OK\n}
   : qq{File BAD\n};

__END__
.....
First Name
.....
.....
Last Name
.....
[download]

This seems to be working for all of the failure cases I can think of. I hope it is of use.

Cheers,

JohnGG

Update: To cope with multiple occurences of "First Name" or "Last Name" in the file you could insert the following after reading the file.

my $fCnt = $fileText =~ /First\sName/g;
die qq{"First Name" occurs more than once\n}
   if $fCnt > 1;

my $lCnt = $fileText =~ /Last\sName/g;
die qq{"Last Name" occurs more than once\n}
   if $lCnt > 1;
[download]

Update 2: That last update was cobblers, it doesn't work properly. Whoops ;(

Update 3: Should have assigned to a list, not a scalar.

my @fCnt = $fileText =~ /First\sName/g;
die qq{"First Name" occurs more than once\n}
   if @fCnt > 1;

my @lCnt = $fileText =~ /Last\sName/g;
die qq{"Last Name" occurs more than once\n}
   if @lCnt > 1;
[download]