Yes having dual cards is better than having a single card. By adding the second card you are making it so there is not an a single point of failure on the HBA's. 
We are having plan to add Compellent SC 8000 single controller + SC220 enclosure to current SAN. Currently, "Front End"  SAN system includes 2 Brocade 300 FC switch connecting to Dell EMC AX4-5 Storage  and 5 PowerEgde servers. My question about Front End of SC8000 connectivity to current SAN: Only 1 FC I/O card with dual FC ports for switch fail-over is enough in this case ? Or we need order two FC I/O card with dual FC ports ? In this plan we limited budget, so can not order dual controller now. The 2nd controller requirement in next time. Thank you for answer from expert vietdung 
Does Compellent SC 8000 single controller apply to Dual Fabric ?