try changing the "Overwrite" to "Never" against each component in the components view.
Overwrite
InstallScript, InstallScript Object
This setting indicates the installation’s behavior when it encounters an existing file with the same name as the one being installed; you can selectively replace each file in a component based on its version number or modification date. To change the behavior, click the ellipsis button (...) in this setting. The Overwrite dialog box opens, enabling you to specify the appropriate run-time behavior.
Tip:If the component consists of files—such as data and configuration files—that end users may have updated, consider selecting the Never Overwrite option.
Files that are associated with a component that has the Never Overwrite option selected for the Overwrite setting are logged for uninstallation; that is, even if such a file is not copied to the target system, because a file with the same name already exists there, that file is removed when the application is uninstalled. To prevent an already existing file from being uninstalled, select Yes for the Shared setting of the file’s component.
