instead of using a hash where keys and values are strings, use a hash where the keys are strings and the values are references to arrays (so you can put more than one value for a key): 
my %h;
while( <> ) {
  my ($k, $v) = process $_;
  push @{$h{$k}}, $v
}
for my $k ( keys %h ) { #traverse all keys
  for my $v ( @{$h{$K}} ) { #traverse all values for that key
    do_your_stuff $k, $v;
  }
}

[download]
and read perllol, perlreftut, perlref, perldsc... I would prefer you read them in that order, but do as you please!!!
[]s, HTH, Massa (κς,πμ,πλ)

In reply to Re^3: Extracting records with unique ID by massa
in thread Extracting records with unique ID by mmittiga17

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.