Hi,
elaborating on my solution to your previous question, this works for me:

#!/usr/bin/perl

use strict;
use warnings;

use DateTime::Format::Strptime;

my $Strp = new DateTime::Format::Strptime(
                                pattern     => '%Y-%b-%d %T',
                        );

my $infile = 'b2bclient-gateway-heartbeat.log';
my $outfile = 'results.txt';
my($fh_out, $fh);

my %lookup;
my $channel = 'TWO';
my $time_delta = 3600;  # seconds = 1 hour

open($fh_out, '>', $outfile) or die "Could not open outfile: $!";

# open($fh, '<', $infile) or die "Could not open logfile: $!";
# while (<$fh>) {
while (<DATA>) {
    next unless /$channel/;
    $_ =~ m/^(.*) UTC.*refs = (\d+)$/;
    my $dt = $Strp->parse_datetime($1);
    my $timestamp = $dt->epoch();
    my $refs = $2;
    if ( defined($lookup{$refs}) && $lookup{$refs} + $time_delta <= $t
+imestamp ) {
        print $fh_out "REFS $refs: occurrences at " . $lookup{$refs} .
+ "and $timestamp \n";
        print "REFS $refs: occurrences at " . $lookup{$refs} . " and $
+timestamp \n";
    }
    $lookup{$refs} = $timestamp;
}

close $fh_out;
#close $fh;

__DATA__
2008-Jan-06 00:00:01 UTC (GMT +0000) - Poll: channel = ONE, refs = 595
+166299
2007-Jan-06 00:00:01 UTC (GMT +0000) - Poll: channel = TWO, refs = 595
+159906
2007-Jan-06 00:00:01 UTC (GMT +0000) - Poll: channel = THREE, refs = 6
+59975924
2007-Jan-06 00:00:04 UTC (GMT +0000) - Poll: channel = ONE, refs = 595
+148941
2007-Jan-06 00:00:04 UTC (GMT +0000) - Poll: channel = TWO, refs = 595
+131400
2007-Jan-06 00:00:04 UTC (GMT +0000) - Poll: channel = THREE, refs = 6
+59975924
2007-Jan-06 00:00:04 UTC (GMT +0000) - Poll: channel = ONE, refs = 595
+159906
2007-Jan-06 01:00:05 UTC (GMT +0000) - Poll: channel = ONE, refs = 595
+166299
2007-Jan-06 01:00:06 UTC (GMT +0000) - Poll: channel = TWO, refs = 595
+131400
2007-Jan-06 01:00:06 UTC (GMT +0000) - Poll: channel = TWO, refs = 659
+975924
2007-Jan-06 01:00:07 UTC (GMT +0000) - Poll: channel = THREE, refs = 5
+95148941
[download]

I'm leaving it to you to re-translate the two timestamps into properly formatted dates.
Regards,
svenXY