Somewhat shorter than other suggestions (by using the Date::Time modules):

use strict;
use DateTime::Format::Flexible;
use DateTime::Duration;

my $one_hour = DateTime::Duration->new(hours   => 1);

my %loglines;

while (<DATA>) {
    next unless /TWO/; # only handle log-items with for channel TWO
    my ($time, $ref)  = /(.*) UTC.*refs = (\d+)$/;
    my $dt = DateTime::Format::Flexible->build( $time );
    if (defined $loglines{$ref}) {
        my $difference = $dt->subtract_datetime( $loglines{$ref}->[0] 
+);
        if (DateTime::Duration->compare( $difference, $one_hour) == 1 
+) { # check if difference more than 1 hour
            print $loglines{$ref}->[1], $_, "-------------------------
+\n";
            delete $loglines{$ref}; # reset the item
        }
    } else {
        $loglines{$ref} = [$dt, $_]; # save the item
    }
}

__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]

And the result is:

2007-Jan-06 00:00:04 UTC (GMT +0000) - Poll: channel = TWO, refs = 595
+131400
2007-Jan-06 01:00:06 UTC (GMT +0000) - Poll: channel = TWO, refs = 595
+131400
-------------------------
[download]

As the specification is a bit vague, I have chosen to reset the check once I have found two matching items more than 1 hour apart. You will then need again two new entries in the log more than one hour apart to trigger it.