CoachBob,
Not sure how accurate your test was since fish are cold blooded which means they are the same temperature as the water they are in and as their body temperature lowers, they slow down and do not move far for something to eat. Since you were using a double rig that puts one lure on a different level than the other one and the one they hit may have been the one that was on their level or closest to them.
Just thinking out loud....
Warren
Fly fishing and fly tying are two things that I do, and when I am doing them, they are the only 2 things I think about. They clear my mind.