There are variations in print and color.

The print on the AU CRO 2.50b1 (left) is bolder and the ASU CRO 2.50b2 (right) is finer. I hesitate to describe it as FINE and BOLD, because there is not that great a difference.

The color variation is very subtle (especially for the color challanged like me) and only when the darker CRO 2.50b2 is sandwhiched between the two CRO 2.50b1 chips does it becomes obvious.

The following is high order esoterica, to be skipped by all but the most dedicated.
Also the color of these chips is not consistant from side to side across the face of the chip.
If you match the light edge of the darker chip with the dark edge of the light chip, they will appear identical. But whn you compare the opposite edges there is a distinct and obvious difference in color.