How to change the order of an array in c++

I am try to change the order of an array of char like this :

char arr_char[]="ABCDEFGHIJABCDEFGHIJ";

i used the rand() function in the following code :

#include <iostream>
#include <cstdlib>
#include <ctime>


using namespace std;



int main()
{
  char arr_char[]="ABCDEFGHIJABCDEFGHIJ";
  int arrSize=sizeof(arr_char)-1;

  srand(time(0));

 for(int i=0;i<20;i++)
 {
    cout<<arr_char[rand() % arrSize]<<" ";
 }
}

but the rand function repeat some characters more than twice and i want to change the order of the array in which every characters repeat only twice not more .