use Modern::Perl;

my $lastrow = "";

open my $fh, '<', 'fail.txt' or die $!;

while (my $line = <$fh>)
{
    $line =~ s/\n//g;
    next if !$line;
    
    if ($line ne $lastrow)
    {
        print $line, "\n\n";
        $lastrow = $line;
    }
}

close $fh;

##</code><code>##

hostname1.com

Gateway FAIL

hostname2.com

Gateway FAIL