Michael,
ColdFusion Builder 2 Udate 1 is a full Installer.
If you are on windows OS then installing Coldfusion Builder 2 Update 1 installer will uninstall your previous version and install the updated version, but before uninstalling the previous version it will ask user by displaying a dialog message whether he would like to uninstall the previous version and proceed with installation, if the user accepts then only installer will un-install the previous version and install updated veriosn i.e, ColdFusion Builder 2 Udate 1.
If you are on Mac OS, to install ColdFusion Builder 2 Udate 1 you have to manually un-install the previous version and then proceed with installing the latest version.