The purpose and function of the dummy files is to have a slim version for a fast installation.
Background: For each TYPO3 installation you need the sourcecode and the dummy package (which you can all get here).
If you have a Unix operating system, you can use Symlinks. This enables you to use just one copy of the source files for several installations. The dummy files have to be unique for each installation. So if you install a second, third... installation of TYPO3 on one server, it is enough to put the content of the dummy package into a new folder and set the symlinks to point to the source folder which is already somewhere else.