Amazon PPC campaigns for variations

I’m running Amazon PPC campaigns and I have a few different ones setup, broad, phrase, exact, etc. I was wondering because my product has 2 variations a 4 pack and an 8 pack, should I include both variations in each individual ppc campaign where it says add product or just one of them?? Logically thinking about it I should just include one and then the customer can just click on the other variation if they want let’s say 8 instead of 4. Is that correct?? Thanks in advance everyone!