On some browsers, we have two PHPSESSIDs.
- One PHPSESSID is not set by me anywhere in my script
 - It has HOST (instead of DOMAIN for the PHPSESSID I set) as www.mywebsite.com
 - I have tried deleting it using setcookie: 
setcookie ("PHPSESSID", $_COOKIE['PHPSESSID'], time() - 864000, '/', 'www.mywebsite.com');but this fails. - An attempt to delete cookie using: 
setcookie ("PHPSESSID", $_COOKIE['PHPSESSID'], time() - 864000, '/');results in the PHPSESSID I set being deleted. - I have tried using 
session_nameto rename the SESSION I set. This works but crashed my server severally after some minutes. 
As a result of the double PHPSESSID, some users cannot login.
How do I fix this as I am out of options.