"Duplicate iptables rule detected" warning messages in l3-agent.log file

Issue

• Seeing the following repetitive warning messages in l3-agent.log file which is increasing the log file size:

2017-03-17 10:05:06.241 141544 INFO neutron.agent.l3.ha [-] Router 01d51830-0e3e-4100-a891-efd7dbc000b1 transitioned to backup
2017-03-17 10:05:07.828 141544 WARNING neutron.agent.linux.iptables_manager [-] Duplicate iptables rule detected. This may indicate a bug
 in the the iptables rule generation code. Line: -A neutron-l3-agent-INPUT -p tcp -m tcp --dport 9697 -j DROP
2017-03-17 10:05:07.829 141544 WARNING neutron.agent.linux.iptables_manager [-] Duplicate iptables rule detected. This may indicate a bug
 in the the iptables rule generation code. Line: -A neutron-l3-agent-INPUT -m mark --mark 0x1/0xffff -j ACCEPT
2017-03-17 10:05:07.830 141544 WARNING neutron.agent.linux.iptables_manager [-] Duplicate iptables rule detected. This may indicate a bug
 in the the iptables rule generation code. Line: -A neutron-l3-agent-PREROUTING -d 169.254.169.254/32 -i qr-+ -p tcp -m tcp --dport 80 -j
 MARK --set-xmark 0x1/0xffff
2017-03-17 10:05:07.831 141544 WARNING neutron.agent.linux.iptables_manager [-] Duplicate iptables rule detected. This may indicate a bug
 in the the iptables rule generation code. Line: -A neutron-l3-agent-PREROUTING -d 169.254.169.254/32 -i qr-+ -p tcp -m tcp --dport 80 -j
 REDIRECT --to-ports 9697
2017-03-17 10:05:16.482 141544 WARNING neutron.agent.linux.iptables_manager [-] Duplicate iptables rule detected. This may indicate a bug
 in the the iptables rule generation code. Line: -A neutron-l3-agent-INPUT -p tcp -m tcp --dport 9697 -j DROP
2017-03-17 10:05:16.483 141544 WARNING neutron.agent.linux.iptables_manager [-] Duplicate iptables rule detected. This may indicate a bug
 in the the iptables rule generation code. Line: -A neutron-l3-agent-INPUT -m mark --mark 0x1/0xffff -j ACCEPT
2017-03-17 10:05:16.484 141544 WARNING neutron.agent.linux.iptables_manager [-] Duplicate iptables rule detected. This may indicate a bug
 in the the iptables rule generation code. Line: -A neutron-l3-agent-PREROUTING -d 169.254.169.254/32 -i qr-+ -p tcp -m tcp --dport 80 -j
 MARK --set-xmark 0x1/0xffff
2017-03-17 10:05:16.485 141544 WARNING neutron.agent.linux.iptables_manager [-] Duplicate iptables rule detected. This may indicate a bug
 in the the iptables rule generation code. Line: -A neutron-l3-agent-PREROUTING -d 169.254.169.254/32 -i qr-+ -p tcp -m tcp --dport 80 -j