title: UDP multiple client receiving from same source
body: <p>I have a question where 2 or more client on host A try to receive from host B with exactly the same address and port number.</p>
  
  <p>Suppose we have host A and there are 2 thread running on it. A.thread_a sends a packet to B port xxxx. Then it does recvfrom(B, xxxx). At the same time, A.thread_b does the same recvfrom() call with same IP and port number. B, after receiving request from A.thread_a, sends data by sendto(A, yyyy). Who would receive the response, A.thread_a or A.thread_b?</p>