Hi,
By default if you don't enable load-balancer if both card are in the same group or if you assign the user both group then each card will receive and process the same ECMs, so you don't take any advantages of having twice the same cards.
I think that you should have enable the load-balancer in your configuration.
Set both card in the same group, and enable load-balancer. You can define the load-balancing strategy that fits your needs.
If both card provide different options then it is adviced to create services and define them on the card (to avoid useless queries) but the load-balancer will also self learned the good and bad SIDs on each card.
But be carefull that if you rely on the load-balancer self learning you need to store the load-balancer on a permanent location, otherwise after each restart of the box, you will lose load-balancer information and it will restart to learn which SID is valid for which card.
Pr2