So the first request costs 100 units of carbon and is cached, user 1 pays 100 units. The second request then comes from the cache so is served from the cache f

So the first request costs 100 units of carbon and is cached, user 1 pays 100 units. The second request then comes from the cache so is served from the cache for just 10 units. Does user 2 pay 10, or do they pay 55 and user 1 gets a rebate of 45 units?