eth1 active on secondary controller on PS6210

We stumbled upon an issue that has us scratching our heads.  We were getting ready to move the 10Gb cables on the standby controller to a new set of switches, but eth1 was showing activity on that controller.  I'll attempt to post a couple images, but essentially it looks like this:

Controller 0 = secondary   f/w: v9.1.4   boot time: 7/22/2021
Controller 1 = primary   f/w: v9.1.4   boot time: 6/1/2021

eth0   10Gbps   status = up   controller = primary
eth1   10Gbps   status = up   controller = secondary

Since we didn't think it was possible to have both controllers with activity at the same time, can someone help explain what we're seeing?  We ended up pulling the eth1 cable from the primary controller (since it didn't show any activity), and sure enough, it didn't miss a beat/ping.