From official support perspective running multiple instances of Portfolio Server 2007 on single server is not a supported scenario. Even the setup program for the tool has no way to achieve the same.
But from development and testing perspective sometimes it is more than handy to run multiple instance on same server (especially when you want the instance to have same set of configuration / customization).
Follow the small tricks below to achieve the same:
Warning -
Please check the licensing requirement with local licensing expert and this is not an supported scenario.