iSCSI controller reporting exactly double of expected I/O

I have a PowerVault MD3220i with a multipathed SAN. Using the performance monitor in MDSM, the RAID controller will report far more traffic than all of the virtual disks combined. How is this possible? Shouldn't the IOPS at the controller be the sum of the IOPS of each individual disk? Also, I noticed that the maximum MBs/sec at the controller is EXACTLY double what is reported a the disk level. Are my IOPS being duplicated some how?