Unable to get identical results when using TRNG

In the following code, I expect that by using TRNG instead of default engine of c++, I can get identical results, but this will not happen. In each run, the final result is a bit different. What mistake I am making that I cannot get the exact digits?

#include <cmath>
#include <random>
#include <iostream>
#include <chrono>
#include <cfloat>
#include <iomanip>
#include <cstdlib>
#include <trng/yarn2.hpp>
#include <trng/mt19937_64.hpp>
#include <trng/uniform01_dist.hpp>
using namespace std;
double function(double x) {
    return cos(x);
}

int main() {
     const int N = 1000000;

   // std::mt19937_64 r(seed);
    
    double sum = 0.0;

    //uniform_real_distribution<double> u(0.0f, nextafter(1.0f, DBL_MAX)); 
   
   
    trng::yarn2 r;
    //trng::mt19937_64 r; 
    trng::uniform01_dist<double> u;
    #pragma omp parallel  num_threads(6)   
    {
    #pragma omp for reduction (+: sum)
    
    for (int i = 0; i<N; ++i) {
        //double x = distribution(g);
        double x= u(r); 
        x = (-1.0) * log(1.0 - x); 
        sum = sum+function(x);
    }
    
    }
    double app   = sum / static_cast<double> (N);
    cout << "Approximation is: " <<setprecision(17) << app <<endl; 
    return 0;
}