Fabric configuration for dual node compute cluster

I have a two server compute cluster with each server have 2 CPU’s. I have installed two CONNECTX-7 400gb infiniband cards in each server (total of four cards). in each server there is one card in a PCIE slot that is close to each CPU. I have made two direct connections between the servers. I have two subnet managers running for each of the direct attached IB cards. When I run MPI to discover the fabrics available, only a single MLX fabric is identified. Does the MLX fabric abstract the two separate network links from MPI? I would have thought that I would need to pin specific MPI processes to the CPU that was closest to a particular NIC.