I took a guess here since these 11-20 and 1-10 things look suspiciously like dates. Now maybe these are chapter numbers or something like that? I'm not sure.

One point is that the normal alpha-numeric sort works if you have leading zero'es. Otherwise, the sort order will not be numeric. So I just added a leading zero for the single digits, this is what you would need to sort chapters or dates easily.

Then I used a hash to count the number of occurences of each digit combo, sorted by that number combo and printed result.

#!usr/bin/perl -w
use strict;

my %date_hash;

my @data = qw(
    NCLEGEND-11-20
    NCLEGEND-11-20
    NCLEGEND-11-2
    NCLEGEND-1-10
    NCLEGEND-1-10
    NCLEGEND-1-10
    NCLEGEND-1-20
    NCLEGEND-1-20);

foreach my $line (@data)
{
   chomp ($line);    #needed if @data is a file handle
   $line =~ s/-(\d)-/-0$1-/; #add leading zero for month
   $line =~ s/-(\d)$/-0$1/;  #add leading zero for date

   my $date = ($line =~ m/NCLEGEND\-([\d-]+)/)[0]; #get the "num" part
   
   $date_hash{$date}++;
}

foreach my $date (sort keys %date_hash)
{
    print "$date   $date_hash{$date}\n";
    #just print "$date\n"; if no need for counter value
}

__END__
Prints:
01-10   3
01-20   2
11-02   1
11-20   2
[download]

Update: This is such an important part of being easily to sort reports by date, that some "amplification" is justified: "2009-08-05" is FAR superior to just "2009-8-5", because the natural alpha sort order will do the right thing for the longer string with leading zero'es. For times, same thing goes: 01:25 is FAR better than 01:25 AM and if you mean 01:25 PM, use 24 hour time 13:25. "2009-08-05 13:25" can be sorted against "2008-08-15 01:25" with just the basic sort in Perl.