In my line of work, this would be called a 'clue'.

This is the original scan of the PhotoShopped chip:

I used this one scan, pasted twice, onto a new canvas, so that I would have identical coloration and dimensions on both of the to-be-altered chips. The intent there was to NOT have answers along the lines of, the blue inserts on A are a different shade than the blue inserts on B. Or, that chip A is bigger than Chip B. Or, the background color of the inlay (white) is darker on chip B than it is on chip A.

So, the above image was used twice to create the side by side image of chip A and chip B. I then altered between 5 and 10 things on chip A and between 5 and 10 different things on chip B, to get the final contest image, below.

For some, seeing the original, un-retouched scan may help in finding the elusive differences, especially for those with "finds" that are closer to 10 than they are to 20.

As I've stated already, every difference that I made has been observed, however, there is one difference that has NOT been appropriately described by anyone (several people have a half credit). Also, there is a second, 'difficult' difference that has been fully described by most of the people that spotted, but has been mischaracterized by others (they get a half credit) and the closest player is 2 half credits away from a win!