How can I start one servo clockwise, and other servo anticlockwise simultaneously (mirror)? A single signal from SSC-32 is divided on both servo (Y), but they are revolved proportionally identically in opposite directions.
If the servos are both driven by the same channel on your controller, then one servo would need to be modified for reverse rotation - something that would require reversing both the direction of the motor’s rotation and the action of the feedback pot. It can be done, but there are usually easier ways to achieve the same effect.
If they’re driven by different channels on the SSC-32, you can issue a “group move” command, which would have them both starting and ending their motion at the same time. then it would simply be a question of commanding them to positions that are in equally offset from the starting point, but in opposite directions from it.
Couldn’t you just spin the motor around on one servo?
Yes, the servos are both driven by the same channel on SSC-32.
My system is driven by RIOS.
The servos are moving the same axle of arm.
They are mounted closely covers to each other.
Accordingly, to revolve an ax, they must be revolved in various directions.
As far as I understood, I must change placed the contacts of motor and to switch two outer wires on a potentiometer of the servo.
Did anybody do similar?
You have the right idea. Just swap the motor wires and the outer two wires on the pot.
The only thing is that some servos have the motor soldered directly to the PCB, in which case you won’t be able to do this. But if it has wires between them, you should be fine.
You could just flip one servo over. If the servo horns are facing each other then it’s going to have the opposite direction automatically. This will work if you can modify the mechanical assembly. 
Reversing the motor wires only reverses the rotation of the servo, but the feedback to the electronics remains the same, so a servo so modified would ‘correct’ in the direction away from where you want it to go. As noted in others’ answers, in order to reverse a servo’s rotation internally, you also need to reverse the outer wires of the feedback pot so that the electronics have an accurate idea of where it’s pointing.
Also as noted above, sometimes the motor is soldered directly to the board, which makes things more complicated. sometimes this prevents this “mechanical reversal” from working, depending on the construction of the servo. Similarly, some servo pots are connected to the board not by flexible wires, but by long, uninsulated leads to the pot itself. This complicates things too, but it can usually be overcome.
Years ago, mechanical reversal of servos used to be the only way to cheaply obtain reversed servo motion, when not every R/C controller featured servo reversing. A few manufacturers even went so far as to sell reverse-rotation servos, at a somewhat higher cost than their regular ones.
With a servo controller being driven by a micro, it’s pretty much a moot point anyway, since you can make a minor change to your code, and you’re going backwards. Driving it with other software depends on how it’s written, and how significantly your design is modified from the design that the software is written to work with.
Still, in many cases, a simple repositioning of the servo will get you the desired output, while proving easier to implement than any of the above solutions.
If the servo controller is being driven by a PC, one can reverse the servo rotation in the software being used. I made a simple program to use a joystick to operate a servo based pan/tilt cam. Origionally the pan servo went to the left when the stick was pushed to the right. I made a simplechang so the cam would rotate to the right when the joystick was pushed to the right. The Hitec HS-422 would be the ideal servo to modify if both the motor and the pot are still connected to the board with wires as shown below instead of directly soldered. I also found some servos rotate in different directions. Tower Hobbies standard servo and the Hobbico servos rotate in opposite directions.
Wow! I did it!
For 805 it works fine. I made a arm with loading to 1.9kg (L=1m).
I’m sure I’m not the only one who would like to see this arm.
Can you post pics? maybe a video?
A project while is not ready completely. Only two shoulders:
I do the arm for a heavy HDMI camcorder. It may be will complete in 3 weeks. Important, that all began to work correctly and maintains the huge loadings. A few details are not yet enough:(