Your use of the 'double-dipping' term is still too kind to the ISP's. There's already double-dipping going on. You, the user, pay for your bandwidth. Netflix also already pays for its bandwidth. So in a sense even a neutral net double-dips, charging both ends of the pipe. (Contrast this with the old-school 'caller pays' model of telephony, which the carriers successfully broke with the advent of cell phones.)
What Comcast now argues is that Netflix doesn't pay enough - because they pay their ISP, rather than Comcast directly, and the other ISP doesn't pay Comcast enough in the peering and transfer agreements. That's an attempt to triple dip: now in addition to charging both ends of the pipe for the data, Comcast wants to charge the server end again because it's not on their network segment. (And then, by extension, even if it is on their network segment, well, because they can.)
Next comes the quadruple-dip: telling the end user that Netflix is a 'premium service' and charging the end user for the privilege of streaming the bits that he's already paying for, because the server operator has also been charged for the privilege of streaming the bits he is already paying for.
Al least two of these four charges (user bandwidth, server bandwidth, server premium access fees, user premium service fees) are nothing more than monopoly rent. And the cable internet providers own a monopoly in most areas of the country. (I can't get copper or fibre DSL: my home phone has a wireless terminal, and the copper to my house is no longer maintained. So for me it's Time Warner or wireless. Terrestrial wireless is many times the cost, and satellite is even worse.)
As you correctly point out, the providers enjoy a monopoly because of the priceless government subsidy that gives them access to their rights of way. The price for that access should be public service.