You cannot share vtkGenericOpenGLRenderWindow instances between two QVTKOpenGLNativeWidgets. All rendering objects in VTK cannot be shared in general. You’ll need to create different vtkGenericOpenGLRenderWindow instances for each of the vtkGenericOpenGLRenderWindow instances. You can use the same vtkSphereSource, but will need different mapper, actor and renderer for each of the vtkGenericOpenGLRenderWindows.