I have tried this

# subroutine for file downloading and moves to corresponding location
        sub file_download {
                my @temp_download_file_names=@{$_[0]};
                my @temp_download_url=@{$_[1]};
                my $dir_path=$_[2];
                my $dir_name=$_[3];
                print "\n\n Please Wait file is Downloading \n\n";
                for(my $ii=0;$ii<=$#temp_download_file_names;$ii++){
                        $mech->get($home_url.$temp_download_url[$ii]);
                        $http_response=$mech->res();
                        if($http_response->is_success){
                                $filename=$http_response->filename();
                        }
                        else {
                                $filename="untitled";
                        }
                        $mech->save_content($filename);
                        system "mv ./$filename $dir_path$dir_name/";
                        print " File name",$filename," is Downloaded \
+n\n";
                        $mech->back();
                }
        }
}
[download]

How Can i check the download file is updated or already downloaded???

The following may help:

#!/usr/bin/perl
use warnings;
use strict;
use WWW::Mechanize;

my $url = 'http://perlmonks.org/?';
my $mech = WWW::Mechanize->new();
my $response = $mech->head($url);
my $modDate = $response->header('last-modified');

if (defined $modDate) {
    print "Modification date: $modDate\n";
} else {
    print "Last modification date not available\n";
}
[download]

Prints:

Modification date: Wed, 25 May 2016 07:45:13 GMT
[download]

Premature optimization is the root of all job security