This will also save it for you: 

use strict   ;
use warnings ;

my @clean_data ;
my %track_hash ;

while( <DATA> ) { 
    my $line = $_  ;
    chomp( $line ) ;
    my ( $date, $word_to_uniq, $other_word ) = split( /\s+/, $line ) ;
    next unless( $date and $word_to_uniq and $other_word ) ;

    if( defined( $track_hash{ $word_to_uniq } ) ) { 
    delete( $clean_data[ $track_hash{ $word_to_uniq } ] ) ;
    }

    push @clean_data, $line ;
    $track_hash{ $word_to_uniq } = $#clean_data ;
    
}

@clean_data = map( { ( $_ ) ? $_ : () }  @clean_data ) ;

foreach ( @clean_data ) { 
    print "$_\n";
}

__DATA__
1/2/2013     cgoo     nreuiheru
1/4/2013     doow    reiqrqueih
1/5/2013     hellio    ruieqrhfuepqh
1/20/2013    cgoo    3rhquh4ureyh
1/30/2013    yetil     jerqohgqrij
2/13/2013    hellio   rueqipheruh
2/14/2013    cgoo    wehrig4r74378

[download]

In reply to Re: Data managing problem by tmharish
in thread Data managing problem by manorhce

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.