Assuming you are only concerned with repeated numbers in consecutive lines, then something like this would do (untested): 
use strict;     #### Always have these lines.  
use warnings;   #### They will save you lots of time debugging

use DBI;
use Time::localtime;
use File::Compare;

use XML::Simple; # qw(:strict);
use Data::Dumper;

my $user = "213256";

my @filesToProcess = glob "/export/home/$user/Tests/Match/dummy2*";   
+ #### Need ""s.  ''s do not do variable interpolation

foreach my $file (@filesToProcess)
{
  open(FILE, $file) or die "Can't open `$file': $!";

  my $prev_var = -1_000_000;         #### set this to a value that wil
+l never appear as the numbers you need to check.
                                     #### (Obviously the 2-digit numbe
+rs must be in the range 0 to 99)

  while ( my $line = <FILE> )        #### do NOT read entire files int
+o memory if they are big.  Much better to process them a line at a ti
+me
  {
    chomp $line;

    my $var = substr($line, 10, 2);  #### Do you mean substr($line,   
+ 9   , 2)?  substr() consders the first character to be at offset zer
+o
        
    if ($var != $prev_var)           #### if number is different to nu
+mber in previous line, then process it
    {
       $prev_var = $var;

       ... process $line here ....
    }
  }

  close FILE;
}

[download]

======

Thought #1:

In your example the lines are sorted by the 2-digit number. If that is typical, then at the most you're only going to have to process 100 lines from the huge files.

Is that what you expect?

======

Thought #2:

Q: What are you supposed to do if you get repeated numbers, but in non-consecutive lines like below? 
AB000000026JHAHKDFK
AB00000003033AFSFAS  = "30" line
AB000000028JHKHKHKJ
AB000000030HJHKH80J  = "30" line
AB0000000324446KJHK
AB000000030LOIKJUJ8  = "30" line

[download]


UPDATE:

Replaced:
foreach my $line ( <FILE> )        #### do NOT read entire files into memory if they are big.  Much better to process them a line at a time
with
while ( my $line = <FILE> )        #### do NOT read entire files into memory if they are big.  Much better to process them a line at a time

Embarassing bug that! In my defence the original code had 'foreach' and I probably just missed it.
Had I written the code from scratch I would (I hope!) have used 'while'. I'm still an idiot though! :)

Thanks very much to Not_a_Number for pointing this out!

In reply to Re: Removing duplicates lines by zork42
in thread Removing duplicates lines by vihar

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.