how about:

open ( IN, "myinput.csv" ) || die "$!\n";
my %data; 
#data is a hash table.  key is COUNT, and vals are 
#key . Type . Error Message vals.  Note that there isn't a 
# very good hash value associated with the set of data,
#as COUNT probably isn't guaranteed to be unique ...

while (<IN>) {
    #split on the comma
    my ( $count, $type, $errMsg ) = split( /,/ );
    print "collision!?!\n" if exists $data{$count . $type . $errMsg };
    $data{$count . $type . $errMsg} = ($type, $errMsg); #ref to list

}
my @sortedKeys = sort keys $data;
print "COUNT\tType\tError Message\n";
foreach my $key ( $data ) {
  print "$key\t$data->{$key}[0]\t$data->{key}[1]\n";
}
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I think I did it without use of libraries ... :) Sozin