Can I use the same PayPal account for different PayPal applications.
Yes you can. The way you do it is to pass the url of the IPN script in the purchase button using the notify_url field. PHP-eSeller, PHP-SecureArea and PHP-KeyCodes are all able to operate on the same PayPal account because they all send the IPN confirm url within the button. This means that if you an application that uses your IPN PayPal account, you can still use withinweb.com applications on your site.
In fact, withinweb.com applications create the and post the data to PayPal dynamically. The relevant information is extracted from the database and, collected together and then posted to PayPal. This method means that you can control the data centrally using the admin panel.