add_executable cannot create target "RobotArmApp" because another target with the same name already exists.

CMake Error at qtbase/lib/cmake/Qt6Core/Qt6CoreMacros.cmake:596 (add_executable):
   add_executable cannot create target "RobotArmApp" because another target
   with the same name already exists.  The existing target is an executable
   created in source directory
   "/home/qt/work/qt/qt5/qtquick3d/examples/quick3d/robotarm".  See
   documentation for policy CMP0002 for more details.
 Call Stack (most recent call first):
   qtbase/lib/cmake/Qt6Core/Qt6CoreMacros.cmake:557 (_qt_internal_create_executable)
   qtbase/lib/cmake/Qt6Core/Qt6CoreMacros.cmake:770 (qt6_add_executable)
   qtdoc/examples/demos/robotarm/CMakeLists.txt:16 (qt_add_executable)
 CMake Error at qtbase/lib/cmake/Qt6Qml/Qt6QmlMacros.cmake:2474 (message):
   Target backendmodule already has a qmltypes file set.
 Call Stack (most recent call first):
   qtbase/lib/cmake/Qt6Qml/Qt6QmlMacros.cmake:555 (_qt_internal_qml_type_registration)
   qtbase/lib/cmake/Qt6Qml/Qt6QmlMacros.cmake:714 (qt6_add_qml_module)
   qtdoc/examples/demos/robotarm/Backend/CMakeLists.txt:3 (qt_add_qml_module)
 -- Configuring incomplete, errors occurred!
 See also "/home/qt/work/qt/qt5/CMakeFiles/CMakeOutput.log".
 See also "/home/qt/work/qt/qt5/CMakeFiles/CMakeError.log".
CMake Error at qtbase/cmake/QtProcessConfigureArgs.cmake:995 (message):
  CMake exited with code 1.