That's a pretty tight grouping -- about 1.6 grams from lightest to heaviest, with 10 balls at 167 grams (rounded to the nearest gram) and 6 balls at 168 grams.
I was glad to see the other weights. I was concerned that my scale was reading a little light since none of Centennials actually measured at a full 6 ounces and my red dot ball weighed in at 5.92 oz. or 167.82 grams.
Well if I got Counterfeit Aramyth Tournament Balls, I would personally contact the supplier, and ask they be replaced. Who did you buy them from, the e-bay bandit, or a reputable supplier?