This can easily be confirmed bu going to
settings>about>software information> build number
if there it says CUCC then you have CUCC install that one only.
SuperSU does not come preinstalled on any phone, it simply means someone used the phone & tried to root it, it may have failed & he then returned the phone within 7 day replacement warranty & you got that phone as repacked. Check with your dealer.
Highly unlikely that this error can happen from asus.
Dealer wont do it to each headset it will take many days doing it, either the earlier buyer did that or you actually have CUCC but had an impression that you have WW. However if you have cucc then you can follow the procedure & convert it to ww. Google search will give yoy links for doing it.
I checked settings>about>software information> build number and it shows that I have WW. But when I enter recovery and sideload the firmware upgrade via adb the update fails saying my Device SKU is CUCC and I have a WW OTA.
And yes I only installed SuperSU(synced from my previous phone) without rooting and when I open it asks if I want to update the binary normally or via twrp/cwm... so it looks like I got a second handed device packed new.
The only problem I'm having is that, the method to switch from CUCC to WW failed and now my phone keeps rebooting itself if I open anything application or settings related and the micro sd is suddenly not detected. I have a huge feeling that reflashing the ROM fresh will fix the problem since I've had so many weird issues like this fixed easily by flashing a stock rom(my previous S3) but sadly so far it doesn't seem like anyone has uploaded a stock zenfone 6 rom.
I also have a question, if you want to update the firmware does the newest update show from the system update at settings? Because mine doesn't, it kept saying I have the latest but I obviously didn't. And correction I didn't have 1.17 but I had the 1.16 version.