If you put 2 servos opposite each other when the same signal is served they will spin in opposite directions of each other. One surface will go up and one down. You can reverse by means of the radio or in my case with Hitec's servo programming program for thei digital servos. However that's not an option when I use Savox servos.
Also a pain when setting up flaps. Yes both servos are the same orientation to each other as soon as you put push rods both either inside or outside the servos you get the same problem. In the old days we ran one pushrod to the inside of the servo and one to the outside. Same with the elevator, one push rod on top, one on the bottom. Digital radios are great!