Hi! If you left an enemy on a spot by fleeing, and then return to the same place, you don't roll for another enemy, just fight the one that stayed here. That's RAI, but if you'd like to make your run harder, or if you feel that "fiction" suggest another enemy could join the one you've left here - you can improvise, adapt, and make your own rules on top of the text-as-wrtitten, at the end of the day it's a solo rpg, not a board game :)