Index: branches/5.2.x/core/kernel/managers/scheduled_task_manager.php
===================================================================
diff -u -N -r16513 -r16665
--- branches/5.2.x/core/kernel/managers/scheduled_task_manager.php	(.../scheduled_task_manager.php)	(revision 16513)
+++ branches/5.2.x/core/kernel/managers/scheduled_task_manager.php	(.../scheduled_task_manager.php)	(revision 16665)
@@ -1,6 +1,6 @@
 <?php
 /**
-* @version	$Id: scheduled_task_manager.php 16513 2017-01-20 14:10:53Z alex $
+* @version	$Id: scheduled_task_manager.php 16665 2021-01-11 08:57:40Z alex $
 * @package	In-Portal
 * @copyright	Copyright (C) 1997 - 2010 Intechnic. All rights reserved.
 * @license      GNU/GPL
@@ -124,6 +124,11 @@
 		$site_domain_id = $site_helper->getDomainByName('DomainName', DOMAIN);
 
 		foreach ($events_source as $short_name => $event_data) {
+			// Scheduled task was updated from another process.
+			if ( $this->getLiveData($short_name) != $event_data ) {
+				continue;
+			}
+
 			if ( $site_domain_id && $event_data['SiteDomainLimitation'] != '' ) {
 				$site_domains = explode('|', substr($event_data['SiteDomainLimitation'], 1, -1));
 
@@ -152,6 +157,22 @@
 	}
 
 	/**
+	 * Returns LIVE scheduled task data.
+	 *
+	 * @param string $short_name Short scheduled task name.
+	 *
+	 * @return array
+	 */
+	protected function getLiveData($short_name)
+	{
+		$sql = 'SELECT *
+				FROM ' . $this->Application->getUnitOption('scheduled-task', 'TableName') . '
+				WHERE Status = ' . STATUS_ACTIVE . ' AND Name = ' . $this->Conn->qstr($short_name);
+
+		return $this->Conn->GetRow($sql);
+	}
+
+	/**
 	 * Runs scheduled task based on given data
 	 *
 	 * @param Array $scheduled_task_data
@@ -220,4 +241,4 @@
 			'Name = ' . $this->Conn->qstr($scheduled_task_name)
 		);
 	}
-}
\ No newline at end of file
+}