IPv6 multicast using same port on different IP addresses results in one receiver getting no traffic

Issue

• IPv6 multicast using same port on different IP addresses results in one receiver getting no traffic
• Issue with using same ports on different IP addresses for sockets
• Reusing port number for receive sockets does not work with RHEL7. Two instances of a software are configured to receive multicast messages using different multicast addresses but same port number.
  • The same multicast receive code works with RHEL6.
  • The instance that comes/starts up second always receives the message and the other running instance stops receiving.
  • The two senders transmitting packets with different multicast addresses and same port number but on the same interface.