Every product is priced by what is actually in it: pence per gram of mushroom extract, worked out from the label. Front-of-pack numbers are usually the raw mushroom a dose is equivalent to, not what is in the pack, so they are not used here.
Each row says when we last confirmed its price. A product sold by more than one shop appears once per shop, because they are different purchases at different prices, and we do not yet link them to each other.
A few packs state what a dose is equivalent to in raw mushroom, and the extraction ratio, but never how much extract is actually in them. Those are priced by dividing one by the other and marked Worked out, not stated, because the arithmetic is the brand’s and the figure is ours.