2 ZWAVE Sticks?

Hello. Is it possible to use two sticks with Zwave for two separate nets with one openhab?

I think you can add two separate Z-Wave Serial Controller things as long as they have a distinguishable port in /dev/tty.

Yes. Furthermore, if you follow Share Z-wave dongle over IP (USB over IP using ser2net / socat ) guide you can put the second one on a RPi or other SBC and place the second one in a better location and connect to the controller remotely.