Now I used the Vcc Output (3.3V) as described to enable a A4988 Stepper Driver (Vdd 3-5.5V) as described here:
I hooked everything up properly, and one Blueduino lost completely serial (unable to connect anymore). I hooked up the second, and the setup worked, but now always when I try to upload the sketch, the upload works, but the Arduino IDE looses connection to the serial, and the serial number increments on one.
So I connect to cu.usbmodem18, upload a sketch (the sketch looses its connection but works), and the device shifted to cu.usbmodem19.
I have all the devices in my MacOS Network Configuration (usbmodem1-19) and I have the devices in /dev/ce.* as well