#!/usr/bin/perl

use feature qw/say/;
use warnings;
use strict;

open my $file1, "<", "test1.txt" or die "Could not open first file: $!\n";
open my $file2, "<", "test2.txt" or die "Could not open second file: $!\n";

while(my $line1 = <$file1>) {
  my $line2 = <$file2>;

  chomp ($line1, $line2);

  my ($key1, $num1, $str1) = split /\s+/, $line1;
  my ($key2, $num2, $str2) = split /\s+/, $line2;

  if($str1 ne $str2) {
    say $line1;
    say $line2;
  }
}

close $file1 or die "Could not close first file: $!\n";
close $file2 or die "Could not close second file: $!\n";