I think it prevents a proper understanding of IP to think of intellectual works as non-excludable/non-rivalrous. That only follows from the IP maximalist’s notion that intellectual works are universal, supernaturally pervasive goods, that the monopolies of copyright and patent protect as the property of their rightful owners.

The thing is, intellectual works are not universals. They are not supernaturally able to collapse into a single object by dint of similarity, and hence able to belong to a single owner. Intellectual works are always discrete physical instances. Their similarity (even indistinguishable) confuses us into mistaking them as the same object.

So, don’t be blinded by the similarity. Realise that all intellectual works are independent objects, copies or not. Each instance is the property of its possessor.

From that more natural (non-supernatural) understanding you can then recognise intellectual works as rivalrous and excludable.

Even though we may mistakenly believe we have the same Tom Jones CD, we do not. You have yours, and I have mine. You can’t use my CD whilst I’m using it, I can exclude you from my CD, and vice versa. The indistinguishable similarity of these CDs does not cause them to collapse into a single object, nor does it permit a distant owner of all likenesses to supernaturally govern the use of their property.

It is the unnatural monopoly that gives rise to the idea of supernatural ownership, not supernatural ownership that gives rise to the need for a monopoly to protect it.