It could be a case that the supplier ran out of one kind of cap and in order to fill the order, they used a different cap. I would suggest opening up a cap from each bottle and comparing the powder inside. If you have a scale that will weigh in mgs, I would also weigh the powder from each. If things aren't jiving, I would get a hold of the company you bought them from and the company that produced them and see what they have to say.