Are you trying to run two separate applications? Or are there two networks in one application?
In OpenVINO, you aren't able to specify which device to use for which network. Instead it will use the first NCS device that is available.
I think it's possible to run two different networks in one application with one of more NCS devices. There is a C++ application that uses two different networks with one device (you'll need multithreading in order to see faster speeds using multiple devices):
Each network will have to have its own read statement. See https://github.com/tomepetty/ncappzoo/blob/openvino/apps/gender_age_lbp_openvino/cpp/run.cpp#L155.
After that, each network will have its own input and output prep sections:
After that part, each network will have its own inference request:
Each inference request will have their own specific results once request.infer() is run.
Please let me know if this answers your question.