Can't get 5120 x 1440 I bought a LG 49WL95C-W 49"  5120 x 1440, but I can't run it at this resolution with my MacBook Pro (15-inch, 2018) (it's work fine with my iMac 5K.

It's seems that max I can get is 3840 x 1080 (although the screen menu/information display a current resolution of 5120x1440 which is wrong according to MacOs)

I tried HDMI (2.1) and USB-C (same cable than the iMac 5K)
I install a third party software too, but I have the same 3840 x 1080 limit.

According to the computer specs, I should be able to run two monitor at this resolution.

Also, weirdly on system preference, I have two monitor listed (the same one)

What do I do wrong?
I still don't understand why the system detected two screen, but I noticed "miror display" was enable. 
Disabled bring the monitor list to one and at full resolution