if RegKeyExists({#IncompatibleArchRootKey}, RegKey) then begin
if MsgBox('{#NameShort} is already installed on this system for all users. Note that both versions will be installed simultaneously; you might want to first uninstall the system-wide installation. Are you sure you want to continue?', mbConfirmation, MB_YESNO) = IDNO then begin
if MsgBox('{#NameShort} is already installed on this system for all users. We recommend first uninstalling that version before installing this one. Are you sure you want to continue the installation?', mbConfirmation, MB_YESNO) = IDNO then begin