neutron-sfc is not working with multiple node

While installing Neutron node i got error in neutron-openvswitch-agent.log

ERROR neutron.agent.ovsdb.impl_vsctl [req-1da7347a-3759-4c16-9f25-96566105d0ca - - - - -] Unable to execute ['ovs-vsctl', '--timeout=10', '--oneline', '--format=json', '--', '--id=@manager', 'create', 'Manager', 'target="ptcp:6640:127.0.0.1"', '--', 'add', 'Open_vSwitch', '.', 'manager_options', '@manager']. Exception: Exit code: 1; Stdin: ; Stdout: ; Stderr: ovs-vsctl: transaction error: {"details":"Transaction causes multiple rows in \"Manager\" table to have identical values (\"ptcp:6640:127.0.0.1\") for index on column \"target\". First row, with UUID c7d736b6-057f-4489-9982-919afc53f7a3, existed in the database before this transaction and was not modified by the transaction. Second row, with UUID 088028a4-5053-4230-a407-cd5ac8b87cdc, was inserted by this transaction.","error":"constraint violation"}

But still everything is working perfectly.
Then i started to work on networking-sfc, where i have tried source, destination and all intermediate node on same network. But all the packets are forwarding to first machine and from first machine it is direct sending to destination.

Then i tried with two different networks. Source and intermediate machine on one network and destination on different network. Still problem is sam. Then i found error on compute node neutron-openvswitch-agent.log file, which is

2017-11-29 18:45:48.448 6955 ERROR neutron.agent.linux.utils [req-82671eda-0a95-4265-bd9b-23d18e29d965 - - - - -] Exit code: 1; Stdin: group_id=2,type=select,bucket=weight=1, mod_dl_dst:fa:16:3e:82:53:7c, resubmit(,5); Stdout: ; Stderr: OFPT_ERROR (OF1.3) (xid=0x2): OFPGMFC_GROUP_EXISTS
OFPT_GROUP_MOD (OF1.3) (xid=0x2):
 ADD group_id=2,type=select,bucket=actions=set_field:fa:16:3e:82:53:7c->eth_dst,resubmit(,5)

2017-11-29 18:45:48.448 6955 ERROR neutron.agent.common.ovs_lib [req-82671eda-0a95-4265-bd9b-23d18e29d965 - - - - -] Unable to execute ['ovs-ofctl', 'add-groups', 'br-int', '-O OpenFlow13', '-']. Exception: Exit code: 1; Stdin: group_id=2,type=select,bucket=weight=1, mod_dl_dst:fa:16:3e:82:53:7c, resubmit(,5); Stdout: ; Stderr: OFPT_ERROR (OF1.3) (xid=0x2): OFPGMFC_GROUP_EXISTS
OFPT_GROUP_MOD (OF1.3) (xid=0x2):
 ADD group_id=2,type=select,bucket=actions=set_field:fa:16:3e:82:53:7c->eth_dst,resubmit(,5)

I am using OVS version 2.6.1.
I am using same commands for creating port pair, port pair group, flow classifier, port chain which is given in tutorial.

Can anyone please explain why this error is coming and sfc is not working with multiple intermediate node.