i guess there are many ways to do it, but i was thinking of create a hash using the type and pos as key: 
my $hash = {};
foreach my $line ( <DATA> )
{
    my ( $id, $type, $pos ) = split /\s+/, $line;
    $hash->{ $id } = { id   => $id,
                       type => $type,
                       pos  => $pos,
                     };
}

my $dup_hash = {};
foreach my $id ( keys %{ $hash } )
{
    my $type_pos = $hash->{ $id }{type} . '_' . $hash->{ $id }{pos};
    $dup_hash->{ $type_pos }{count}++;
    $dup_hash->{ $type_pos }{id} = $id;
}

[download]
You can use the $dup_hash to check for duplicates etc. 
$dup hash = {
  '1_10' => {
              'count' => 1,
              'id' => '1'
            },
  '1_11' => {
              'count' => 2,
              'id' => '2'
            },
  '1_15' => {
              'count' => 1,
              'id' => '4'
            },
  '2_5' => {
             'count' => 2,
             'id' => '5'
           },
  '2_7' => {
             'count' => 1,
             'id' => '7'
           }
}

[download]

In reply to Re: Identifying duplicates in array or hash based on a subset of data by duyet
in thread Identifying duplicates in array or hash based on a subset of data by Anonymous Monk

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.