This mode can be used when 2 pumps are installed in a heating/cooling circuit. This can ensure redundancy.
One pump takes over the task of the "main pump" and the other is used as a "backup pump".
Once one of the two pumps fails, the other can step in for it.
To achieve a synchronous load of the two pumps they can be used alternately.
This mode can be activated in the parameter "General":