C++11 rvalue issue

I don't know how come the following example output, can anyone tell me? Thanks in advance!

#include <iostream>
#include <algorithm>

class A
{
public:

    // Simple constructor that initializes the resource.
    explicit A(size_t length)
        : mLength(length), mData(new int[length])
    {
        std::cout << "A(size_t). length = "
    << mLength << "." << std::endl;
    }

    // Destructor.
    ~A()
    {
  std::cout << "~A(). length = " << mLength << ".";

  if (mData != NULL) {
            std::cout << " Deleting resource.";
      delete[] mData;  // Delete the resource.
  }

  std::cout << std::endl;
    }

    // Copy constructor.
    A(const A& other)
      : mLength(other.mLength), mData(new int[other.mLength])
    {
  std::cout << "A(const A&). length = "
    << other.mLength << ". Copying resource." << std::endl;

  std::copy(other.mData, other.mData + mLength, mData);
    }

    // Copy assignment operator.
    A& operator=(const A& other)
    {
  std::cout << "operator=(const A&). length = "
           << other.mLength << ". Copying resource." << std::endl;

  if (this != &other) {
      delete[] mData;  // Free the existing resource.
      mLength = other.mLength;
            mData = new int[mLength];
            std::copy(other.mData, other.mData + mLength, mData);
  }
  return *this;
    }

    // Move constructor.
    A(A&& other) : mData(NULL), mLength(0)
    {
        std::cout << "A(A&&). length = " 
             << other.mLength << ". Moving resource.\n";

        // Copy the data pointer and its length from the 
        // source object.
        mData = other.mData;
        mLength = other.mLength;

        // Release the data pointer from the source object so that
        // the destructor does not free the memory multiple times.
        other.mData = NULL;
        other.mLength = 0;
    }

    // Move assignment operator.
    A& operator=(A&& other)
    {
        std::cout << "operator=(A&&). length = " 
             << other.mLength << "." << std::endl;

        if (this != &other) {
          // Free the existing resource.
          delete[] mData;

          // Copy the data pointer and its length from the 
          // source object.
          mData = other.mData;
          mLength = other.mLength;

          // Release the data pointer from the source object so that
          // the destructor does not free the memory multiple times.
          other.mData = NULL;
          other.mLength = 0;
       }
       return *this;
    }

    // Retrieves the length of the data resource.
    size_t Length() const
    {
        return mLength;
    }

private:
    size_t mLength; // The length of the resource.
    int* mData;     // The resource.
};

#include <vector>

int main()
{
   // Create a vector object and add a few elements to it.
   std::vector<A> v;
   v.push_back(A(25));
   v.push_back(A(75));

   ::std::cout << "----------------------" << std::endl;

   // Insert a new element into the second position of the vector.
   //v.insert(v.begin() + 1, A(50));
   return 0;
}

ouput:

A(size_t). length = 25.
A(A&&). length = 25. Moving resource.
~A(). length = 0.
A(size_t). length = 75.
A(A&&). length = 75. Moving resource.
A(const A&). length = 25. Copying resource.   // how come these two lines?
~A(). length = 25. Deleting resource.
~A(). length = 0.
----------------------
~A(). length = 25. Deleting resource.
~A(). length = 75. Deleting resource.