Mocking chain value twice throws exception

    public struct SpecialValue
    {
        public double X
        { get; set; }
        public double Y
        { get; set; }
       
    }
    public class Typemockclass
    {
        public SpecialValue pt1
        { get; private set; }
        public SpecialValue pt2
        { get; private set; }

    }

        [Test, Isolated]
        public void  testSpecialValue()
        {
            Typemockclass mock = Isolate.Fake.Instance<Typemockclass>(Members.ReturnRecursiveFakes);
            Isolate.WhenCalled(() => mock.pt1.X).WillReturn(30);
            Isolate.WhenCalled(() => mock.pt2.X).WillReturn(60);
            
        }

TestCase 'TypeMockTest.testSpecialValue'
failed: TypeMock.TypeMockException : 
*** Cannot use MockAll twice for type SpecialValue
   at ds.a(Constructor A_0, Boolean A_1)
   at TypeMock.MockManager.MockAll(Type type, Constructor mockConstructors)
   at TypeMock.MockManager.Mock(Type type, Constructor mockConstructors)
   at TypeMock.MockManager.b(Object A_0, String A_1)
   at TypeMock.MockManager.a(String A_0, String A_1, Object A_2, Object A_3, Boolean A_4, Object[] A_5)
   at TypeMock.InternalMockManager.getReturn(Object that, String typeName, String methodName, Object methodParameters, Boolean isInjected)
   at SpecialValue.get_X()

        [Test, Isolated]
        public void  testSpecialValue()
        {
            Typemockclass mock = Isolate.Fake.Instance<Typemockclass>(Members.ReturnRecursiveFakes);
            Isolate.WhenCalled(() => mock.pt1.X).WillReturn(30);
          
            
        }