The Oppo R9 was leaked some time ago, and we could have already seen a TV commercial in China for it. And know the company has sent out invites for the launch event, which will take place on October 19. We have also heard about the phones camera: it is based n a new Sony-made IMX398 sensor, so it will be quite powerful device.
The TV ad doesn't mention anything about the R9s Plus model, so we can assume it will be announced at a different point in time. Which means we can expect rather different hardware in it (which is typical for Oppo devices).
We will hear more on October 19.