I was able to code an Multithreaded litle Projekt with two servos and the Arduino Due. The servos from Modelcraft RS2 are cheap and good for what i need them. You can see the signals frequency in this article.
Signal at 1.0 ms
Signal at 2.0 ms
Signal 13.4 LOW and 2.0 ms HIGH
1.0 ms HIGH and 13.4 ms LOW = turn left
2.0 ms HIGH and 13.4 ms LOW = turn riight
1.5 ms HIGH and 13.4 ms LOW = middle position