If the stated supply periods were calculated at one gummy a day, taking two shortens each pack and raises the daily cost.
Based on the page's supply periods, a 2-bottle pack at $158 covers 60 days, or about $2.63 a day before shipping. A 3-bottle pack at $207 over 90 days is about $2.30, and 6 bottles at $294 over 180 days about $1.63.
If those periods assume one gummy a day and you take two, each pack lasts half as long and the daily figures roughly double. That is our assumption, since the page does not state which serving it used.
Confirm with the seller which serving the supply periods assume, then decide on your serving with the label and, if needed, your doctor. A higher serving is not automatically better, and the guarantee window does not extend with a larger serving.