When 2 TCP connections are established at the same time between two peers, SXP drafts specifies one should drop one of the connections. This doesn't happen in ODL SXP at channel activation time, rather as a response to Open MSG, which in turn leads to a situation where SXP nodes try connect second time an Open connection. This fails due to the SXP-135 VSS switchover implementation.

Oxygen:

https://jenkins.opendaylight.org/releng/job/sxp-csit-1node-basic-all-oxygen/251/