So basicaly I can't Install 2 Services through the services part of advanced installer?
As mentioned in the thread, this is unfortunately not supported by Windows Installer.
Would I be able to install multiple services using a custom action that calls up a batch script to do the install?
You can try, but I'm not sure it will work for the same reason. The more elegant solution described by Cosmin in the thread would be to use multiple packages (one for each service) as prerequisites for the main installation.
All the best,