#!/usr/local/bin/perl
use strict;
use warnings;
use Data::Dump qw/pp/;

my %seen_file;
my %Hash_filematches;
my %Hash_filenames;

while ( chomp(my $line = <DATA>)){
        (my $file_name) = $line;
        if ( ($file_name) and ( !$seen_file{$file_name}++ ) ) {
        foreach my $filename(keys %Hash_filenames) {
        print "FILE NAME $file_name\n";
      @{ $Hash_filematches{ $filename } } = grep( /\/\Q$file_name\E#/i, @{ $Hash_filenames{ $filename } });
     #@{ $Hash_filematches{ $filename } } = grep( (/\/\Q$file_name\E#/i && !/\.plf/), @{ $Hash_filenames{ $filename } });--------->@{ $Hash_filematches{ $filename } } stores only the grep of the last $file_name
      }#for loop end
   }#if file_name end
   
for my $key (keys %Hash_filematches) {
  my $value = $Hash_filematches{$key};

   if (scalar @$value) { # check that the arrayref isn't empty
      print "KEY: $key\n";
      print "VALUES: ", join(", ", @$value), "\n\n";
           }
       }
   }

print pp(\%seen_file);
#print pp(\%Hash_filematches);
#print pp(\%Hash_filenames);
__DATA__
file1
file2
file2
file3