#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my %hash = ( 'common line' => ['file1',
			       'file2',],
	     'common line different' => ['file1',
					 'file2',
					 'file3',] );

print Dumper \%hash;

__END__

$ perl test.pl
$VAR1 = {
          'common line' => [
                             'file1',
                             'file2'
                           ],
          'common line different' => [
                                       'file1',
                                       'file2',
                                       'file3'
                                     ]
        };