To illustrate this, here's a tray of regular Oreos(TM), and here's a similarly sized tray of double-stuf(TM) Oreos(TM). And if you were to consider the per-cookie cost, as Mediacom is clearly hoping you will, then yes, double-stuf(TM) Oreos(TM) cost more than regular Oreos(TM).
But foodstuffs such as cookies are not sold by the cookie. They're sold by unit weight (or unit mass if you want to be pedantic). Considered this way, the per-ounce cost of the regular and double-stuf(TM) Oreos(TM) is virtually identical (in this case, about $0.26/oz from this retailer). So if Nabisco(TM) has no reason to charge a premium simply because you consume the cookies in larger units, Mediacom has no such reason, either.
So Mediacom are full of shit.