Paul Stovell discusses a method for managing multiple deployments of a website in a testing environment by using port numbers derived from the release version. By leveraging a PowerShell script, the process calculates a port number for each deployment using the modulo operator on the version's build number, allowing for the retention of a specified number of recent deployments. This approach ensures that older versions remain accessible even after new ones are deployed, with configurations made in the IIS feature of the package step. The port number is stored as an output variable, which can also be used to notify testers via email about new releases and their corresponding port numbers, offering an efficient solution for managing deployment environments.