In the middle of a live VLAN readressing of a 200-node company, I encountered this gem. The ports just kept blinking on even after plugging out the cables. (HP aruba 24 port switch)
One turned off after a reboot.
The lights are combined link/act, not separate link act. left for upper side, right for lower side. 2 and 4 are blinking, 1 and 3 (the empty ports) are not.