In May 2017 I bought a U2415 which I used in combination with some older DELL monitors.
Now I just acquired another two U2415 to replace those older monitors. Unfortunately with the same settings my first U2415 seems more blueish than the new monitors which appear more yellowish.

Could the difference be due to the fact that they most certainly come from different batches?
How can I easily calibrate all three monitors consistently?