Fiora passive doubling

Didnt have the wherewithal to screencap it at the time, but I had an issue with fiora today. I was fighting gnar when the passive decayed right as he was bouncing into a bush. upon exiting, he had two passive marks, but one was only visual which i confirmed by using lunge on each one to check. It only left once I killed him using my ult, at which point it was gone when he came back. It remained both after he left lane and died without my ult being used, however.