Can you show the side view? If the colors are in a pretty exact straight line in the middle of the chip, then it may have been made that way as a sample. Also check the drill hole. It would also show a defining line between the 2 colors inside the hole. Another thing to note is that your inlay on that one side also looks faded, which is more indicative of sun fading. Still its a very cool chip!

2 tone chip:

2 tone insert;