If you want multiple sites in IIS, you can add the sites underneath Default Website.
Doing this will create virtual apps in IIS, so simply going to "localhost/" will not bring you to the site.
When creating the site, right click on "Default Website" and choose "Add Application". Choose the physical path to the wwwroot folder in ASEBA.
Please note, for the second website, their will need to be a separate instance of the wwwroot folder.
For each site, in the web.config file, you will need to change the default URL to : /yourSiteName/signin and /yourSiteName