Same LG27UDseries 4K monitors with different colors

[mitzaotomitza]

I am trying to complete a triple 4K monitor setup with no luck.
LG 27UD68-P monitor is in the center. Left and right are two LG 27UD69P-W.
27UD68-P (center) +27UD69P-W (left and right)
This are the exact factory model numbers.

 

The center monitor 27UD68-P is way brighter than the ones on the sides. Even the left and right monitors are displaying different color even if they are exact the same.
I messed with all the settings the UD69P-W monitors are displaying a yellowish white.
I went over and over the specs of this monitors and only difference I could find in between these models is that the UD68-P has the brightness at 350cd/m2 whereas the UD69P-W has a lower value 300cd/m2.

I would appreciate any ideas about how to fix this issue:
1. return the 27UDP69-W two monitors and get the exact older version 27UD68-P?
2. is there any way I can fine tune the monitors to match the colors. Mostly the whites and the blacks which are faded in the newer model.