Description:
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Hi,
When adding +2 hours  to '2009-10-25 01:00:00', '03:00:00' is obtained, skipping the second '02:00:00' that exists during that night.



Reproduce code:
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Comparison between using +1 hour to the object and adding +3600 to the timestamp :

<?php
$date1 = '2009-10-25 01:00:00';

$obj_date = date_create($date1);
$timestamp = strtotime($date1);

$timestamp += 3600;
$obj_date->modify('+1 hour');
echo '+1 hour<br>';
echo  'timestamp : ' . date('H:i:s',$timestamp) . ' ' . $timestamp . '<br/>';
echo 'date_obj : ' . $obj_date->format('H:i:s') . ' ' . $obj_date->format('U') . '<br><br>';

echo '+2 hours<br>';
$timestamp += 3600;
$obj_date->modify('+1 hour');
echo  'timestamp : ' . date('H:i:s',$timestamp) . ' ' . $timestamp . '<br/>';
echo 'date_obj : ' . $obj_date->format('H:i:s') . ' ' . $obj_date->format('U') . '<br><br>';
?>

Expected result:
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+1 hour
timestamp : 02:00:00 1256428800
date_obj : 02:00:00 1256432400

+2 hours
timestamp : 02:00:00 1256432400
date_obj : 02:00:00 1256432400

Actual result:
--------------
+1 hour
timestamp : 02:00:00 1256428800
date_obj : 02:00:00 1256432400

+2 hours
timestamp : 02:00:00 1256432400
date_obj : 03:00:00 1256436000