Dell M1000e Chassis question

Question about specific view I am seeing. In the Properties page of each blade, in the section WWN/MAC Addresses, there is a display of port- fabric mapping. For a single slot on Fabric B1 and B2 I am seeing two Gigabit Ethernet connections with separate MAC addresses. How is this possible? Do I have two GB network cards mapped to a single connection on a pass-through panel?
From a server view I am seeing one of those ports being down which makes sense but I am not sure how to read this two GB NICs mapped to a single port.