As this is very unlikely, such symptoms could be due to any of a number of other causes
...such as a poor manufacturing process that allowed for inconsistent amounts of active ingredient to be deposited on the pillules. This could lead to a build up of active ingredient that periodically gets deposited. This could be a reasonable explanation for the inconsistent and actually measurable amount of active ingredient found on the pills. This inconsistent amount would fall on a bell curve and at the thin ends of that we have the "nothing at all" and the "way too much" amounts. The fact that the limited number of pills tested did not fall into the "way to much" end of the curve is not only unsurprising, but it would be unexpected. This doesn't mean it can't happen. As 10 families have discovered already.