VS2015 std::async strange

In the below code in VS2015, I'm getting acefbd in the first line, which is correct. but in the 2nd test where I seperate out into individual lines, the output is abcdef.

Is that intended behavior?

#include <future>
#include <iostream>

using namespace std;

void a () {
std::cout << "a";
std::this_thread::sleep_for (std::chrono::seconds (3));
std::cout << "b";
}

void c () {
std::cout << "c";
std::this_thread::sleep_for (std::chrono::seconds (4));
std::cout << "d";
}

void e () {
std::cout << "e";
std::this_thread::sleep_for (std::chrono::seconds (2));
std::cout << "f";
}

int main () 
{
    std::async (std::launch::async, a), std::async (std::launch::async, c),  std::async (std::launch::async, e);

cout << "\n2nd Test" << endl;

std::async (std::launch::async, a);
std::async (std::launch::async, c);
std::async (std::launch::async, e);

}