Can I parallel two X3-Hybrid-G4 inverter, the master one with 2 batteries, the other with no battery?

Yes, you can parallel them like that, but please be advised that it can work only when grid is on, when grid is off, because there is no battery connected to the slave inverter, it will show grid lost fault. So we do not recommend you parallel them like, you had better to connect with the same battery number and quantity、type.