#!/usr/bin/perl

use Data::Dumper;
use strict;

my %count;

for my $i (3..6) {
     my $filename = "file.20020$i";
     open(DATA,$filename);
     while (<DATA>) {
          my ($name) = split(/\s+/,$_);
          $count{$filename}{$name}++;
     }
}

print Dumper %count;