map as associative array destroy object twice

Here is a small program, that traces construction and distruction of
class A objects.
If I use make_pair to insert in a map everything is OK.
If I insert using [], than objects with index 11, 7 and 3 will be
deleted twice and objects with indexes 10, 6 and 2 not deleted at all.
What is wrong ? I am new to standard library.

I use Sun Studio 10: C++ 5.7 Compiler

#include <map>
#include <iostream.h>
using namespace std;

class A
{
public:
A() : i(0)
{
    j = k++;
    cout << "Con " << i << " " << j << "\n";
};

A(int l) : i(l)
{
    j = k++;
    cout << "Con_k " << i << " " << j << "\n";
};

~A()
{
    cout << "Dest " << i << " " << j << "\n";
};

A(const A& a)
{
    i = a.i;
    j = k++;
    cout << "Copy " << i << " " << j << "\n";
};

int i;
int j;
static int k;
};

int A::k = 0;

int main()
{
     cout << "1\n";
     std::string s;
     std::map<std::string, A> mp;

     cout << "2\n";
     s = "A";
     mp[s] = A(1);
     //mp.insert(make_pair(s, A(1)));

     cout << "3\n";
     s = "B";
     //mp.insert(make_pair(s, A(2)));
     mp[s] = A(2);

     cout << "4\n";
     s = "C";
     mp[s] = A(3);
     //mp.insert(make_pair(s, A(3)));

     cout << "5\n";
}