#!/usr/bin/perl
# dirdupes

use strict;
use warnings;
use File::Find;
#*****************Path Variables**********************
our $testpath = 'C:\\Temp\\';
#******************************************************* 

my %dirs;
find(\&dir_names, $testpath);
my @dup_dirs = grep { $dirs{$_} > 1 } sort keys %dirs;
foreach my $list (@dup_dirs) {
	print "$list\n";
}

sub dir_names
{
    return unless -d;
    return unless /[IPD]\d{8}$/;
	$dirs{$File::Find::name} = 1;
	++$dirs{$File::Find::name};
}

##</code><code>##

Output
c:\Temp\hddzip>perl dirdupes.pl
C:\Temp/Alcohol/P12345678
C:\Temp/hddzip/I12345678
C:\Temp/hddzip/P12345678
C:\Temp/hddzip/P12345679
C:\Temp/hddzip/Test1/P12345678
C:\Temp/hddzip/Test2/P12345678

##</code><code>##

#!/usr/bin/perl
# dirdupes

use strict;
use warnings;
use File::Find;
#*****************Path Variables**********************
our $testpath = 'C:/Temp/';
#******************************************************* 

my %dirs;
find(\&dir_names, $testpath);

foreach my $D (sort keys %dirs) {
	if (@{$dirs{$D}} > 1) {
		print "\nFound duplicate directories\n";
		foreach my $dupes (@{$dirs{$D}}) {
			print "$D - $dupes\n";
		}
	}
}
sub dir_names
{
	return unless -d ;
    return unless /([IPD]\d{8})$/;
	my $P00 = $_; #or $1
	if (not exists($dirs{$P00})) {$dirs{$P00}=[];}
	push @{$dirs{$P00}},$File::Find::dir;
}

##</code><code>##

C:\Temp\hddzip>perl dirdupes.pl

Found duplicate directories
I12345678 - C:/Temp/hddzip
I12345678 - C:/Temp/hddzip/Test1

Found duplicate directories
P12345678 - C:/Temp/Alcohol
P12345678 - C:/Temp/hddzip
P12345678 - C:/Temp/hddzip/Test1
P12345678 - C:/Temp/hddzip/Test2

Found duplicate directories
P12345679 - C:/Temp/hddzip
P12345679 - C:/Temp/hddzip/PDF