They sometimes do, but that is an ESX bug, iSCSI should be allowed by default.
I think it was ESX 3.5 that started requiring allowing iSCSI in the security profile, then Update 1 went back to that being default.
Either way if the security profile does not have it allowed you should allow it.
For just 2 nics I'd do one V switch with both nics, one flat network or a VLAN for iSCSI if you know how.
Basically nic redundancy trumps SAN separation.