I'm not sure I can help. Really need to see what's going on... too bad you couldn't post images yet, but you need certain reps to do that..
Maybe if you explained it in clearer English.
You have a player instantiated, and another object of the same type, just copy and pasted? And you have a circle that comes up around your player, and you want to test which enemies are in the circle? Find one enemy that's inside the circle?
Attach an instance variables to your enemies. A Boolean set to false, called isInsidePlayerSight. Then add an event, every tick. Then add another condition, click the type your testing to overlap, and choose is overlapping another object, or oncollision with another object.. Click the circle.. then in the event click the object, set boolean value, turn isInsidePlayerSight to true... Then make a new event foreach of enemy. On the same event add a new condition choose enemy object, then find "is boolean instance variable set".. in that event do what you need to do to each enemy inside that circle.