Multiple Installations

If you re-run an installation after it has already installed on the target system, it will display a maintenance user interface, instead of an installation user interface. This is because Windows Installer detects that the product is already installed, and enters maintenance mode.

Unfortunately, there is no way to prevent this type of behavior in Windows Installer setups. You may however change the product and revision codes every time you change your product version to help users reinstall multiple versions of the same product, or upgrade over an older version.