Adjustments cannot be made to the LCD backlights. On both, open the OSD (On Screen Display) Menu- Other Settings. Choose Factory Reset Enable. Then tweak the first U2312HM using Color Settings- Preset Modes- Custom Color. Once satisfied, move to the second U2312HM and tweak to get a closer match to the first U2312HM. Or, purchase calibration hardware and software.

I know how to set custom colours but this is a workaround rather than a fix and is hampered by no Gamma adjustment available.

 

Running the self test options using monitor A as a reference monitor B Red and Green test screens have a yellow caste, Blue looks like they match although A should be slightly high.

The calibration screens show

A

Offset R114   G103    B113

Gain   R160   G163    B157

B

Offset R107   G118    B113

Gain   R152   G158    B151

 

How are these values generated? 

 

How are these values generated?
* The values are based on the settings in the internal only Factory Service Menu. Entering the Factory Service Menu is not something I can support. Changes could be made in there that could break the monitors.