injection molds were used to get the "thick" and "thin" line variations. This happens on many Bud Jones CIC chips.

While I won't guarantee it, I believe this happens when there is a re-order. Have you looked at both chips under a UV light to see if the plastic formula is also different. (Look for the white to be different shades or the red to be diferent and then for those differences to be consistent with the think/thick line.)

Jim