Hi Felix,
There is no need to pickup two appium servers,
you just use the same port (that’s something nice about appium studio)
from my experience, these issues usually occur due to parallel framework implementation (e.g you have one static driver,or synchronized methods between two parallel tests)
Cucumber & JUnit configuration is tricky for parallel execution
My recommendation :
achieve parallelism by executing two separate Cucumber processes, e.g by running a batch file or shell script
using the batch or shell, pass the device \ os \ suite parameters to the cucumber process
I hope this makes sense, if you have more details you want to discuss, feel free