This message is normal; i.e. nothing to fix.
Dual standby contention means that one (or both) PBX’s discovered that it is in standby mode and the remote peer is as well. Once this condition is detected the PBX’s begin negotiation to determine who should promote.
After a manual failover, or following the failure of one peer, the other peer will detect that no one is in active mode and record the event.
This is a normal condition (so long as it is followed by a promotion by one peer).
