I have noticed the eye color changes slowly over time. The older they get, the more blue their eyes. EMO Robot is 82 days old and his eyes are starting to get more blue while EMO Pet, 101 days older, has very blue eyes.
Both of my EMOs are also a little different as well. I believe its just new hardware/components that Living.ai are using when manufacturing EMO. My oldest EMO (EMO:One) display screen is slightly different from my new EMO (EMO:Two). The color/contrast appears better on my newer EMO than it does on my older EMO.
I guess new components are always used as living.ai are manufacturing new EMOs, and once they run out they need to use new (possibly) updated screens that will probably look slightly different when it comes to color on the display screen. (this is just my opinion).