Getting every BGP prefix twice

[mlindgren80]

I am running frr_4.0-1.debian9.1_amd64.deb on Debian 9. I am peering with an upstream ISP via v6, but getting every prefix twice.

router bgp 2XX914
 coalesce-time 1000
 neighbor 2402:28c0:3::179 remote-as 136620
 neighbor 2402:28c0:3::179 ebgp-multihop 3
 !
 address-family ipv4 unicast
  no neighbor 2402:28c0:3::179 activate
 exit-address-family
 !
 address-family ipv6 unicast
  neighbor 2402:28c0:3::179 activate
  neighbor 2402:28c0:3::179 prefix-list pl2XX914 out
 exit-address-family
!
ipv6 prefix-list pl2XX914 seq 5 permit 2a06:XXXX:2000::/40

Neighbor               V         AS MsgRcvd MsgSent   TblVer  InQ OutQ  Up/Down State/PfxRcd
2402:28c0:3::179       4     136620  298062     812        0    0    0 13:00:23       102996

When the IPv6 routing table is only about 51-52K routes.

# show bgp 2600::
BGP routing table entry for 2600::/29
Paths: (2 available, best #2, table Default-IP-Routing-Table)
  Advertised to non peer-group peers:
  fd65:cb82:303d:c998::a
  136620 174 1239
    2402:28c0:3::179 (metric 1024) from 2402:28c0:3::179 (103.105.50.12)
      Origin IGP, metric 0, localpref 100, valid, external
      Community: 174:21000 174:22013 64512:102
      Large Community: 136620:0:102
      AddPath ID: RX 3, TX 172305
      Last update: Fri Jun  1 01:12:22 2018

  136620 174 1239
    2402:28c0:3::179 (metric 1024) from 2402:28c0:3::179 (103.105.50.12)
      Origin IGP, metric 0, localpref 100, valid, external, best
      Community: 174:21000 174:22013 64512:102
      Large Community: 136620:0:102
      AddPath ID: RX 4, TX 172304
      Last update: Fri Jun  1 01:12:22 2018

My IBGP peer (OpenBGPD, not shown in the config) appears to do the right thing by only receiving 51K prefixes from FRR. Am I just mis-interpreting the output or is there something going on here?

[mlindgren80]

It looks like the cause of the duplicate routes is the addpath functionality. Is there any way of disabling or is it just working as intended?

[kssoman]

I will look at the issue in the master build and also stable/4.0 build