You wish to configure PayPal IPNs for your website. However, you are already using IPN notifications on another website and PayPal will only accept one default URL.
As long as you have enabled PayPal IPNs as directed in this article, you should receive IPN notifications and not have any problems. When we securely send your data to PayPal, we include the correct IPN URL information. PayPal will override the default URL and use the IPN URL information we provide for each transaction.
As always, be sure to run a test transaction before going live to be sure that nothing has changed at PayPal and your IPNs are configured correctly.