overload operator new(), why constructor is called twice?

I can`t understand some problems when learning new/delete overload. Questions:

1. Why new is called before constructor，destructor before delete?
2. Why constructor is called twice when using ::new ?

I've appended the code here:

#include<iostream>

using namespace std;

class MyClass
{
public:
    MyClass() { 
        cout << "My Class is Constructed ！" << endl; 

    }

    ~MyClass() { cout << "My Class is Deleted ! " << endl; }

     static void *operator new(size_t Size)
    {
        cout << "new call" << endl;
        MyClass *p = ::new MyClass;
        return p;
     }
     static void operator delete(void *p)
     {
         cout << "delete call" << endl;
         ::delete p;
     }

};
int main()
{
    MyClass  *p = new MyClass;
    delete p;
    cin.get();
    return 0;
}

output:
new call
My Class is Constructed ！
My Class is Constructed ！
My Class is Deleted !
delete call