Probiotics

I've been buying the Dischem brand of Probiotics Gold for my husband for a long time. Recently my husband says he has to take a double dose to get the same effect as previous. I went online and noticed that the amount of CFU's is 10 billion. However, when I visited the store a week ago, the actual container stated 5 billion CFU's. How can you pay the same price for half lesser strength? I had to buy another product in order to get 10 billion CFU's.