use strict;
use warnings;
 
my %seen;
while ( <DATA> ) {
   next unless /^(<cnt>([^<]+)<\/cnt>)(.*)$/;
   print $seen{$2}++ ? "<TAB>$3\n" : "$1$3\n";
}


__DATA__
<cnt>France</cnt><cmp>ACCOR</cmp>
<cnt>France</cnt><cmp>AGF</cmp>
<cnt>France</cnt><cmp>AIR LIQUIDE</cmp>
<cnt>Germany</cnt><cmp>ALLIANZ INSURANCE</cmp>
<cnt>Germany</cnt><cmp>ALLIANZ PARKWAY</cmp>
<cnt>Germany</cnt><cmp>ALLIED DOMECQ</cmp>
<cnt>United Kingdom</cnt><cmp>LEICESTER CITY FOOTBALL CLUB</cmp>
<cnt>United Kingdom</cnt><cmp>SPENCER GEARS</cmp>
[download]