[unavoidable]

Then you have the reason why you haven't received an answer - your question is framed (almost deliberately) to have no answer. Copyright does not exist "in an object". It _is_ a state-enforced statutory right that "exists" in a "work" whether that work is a movie, music, software, book, etc. The "physical medium" you refer to is merely one copy of the "work" that is copyrighted. The work itself is necessarily incorporeal - it is an intellectual creation of somebody, and lies beyond the mere physical expression. You can do whatever you want with the box or medium - you are entitled to do that, except to the extent that you are limited by protection of the "work" that is copyrighted.

[TheAmazingIdiot]

Then how do you prove your copy is legitimately made copy from the rightsholder?

[SEMW]

You'd show it the same way you prove anything in a civil case: with evidence that, on the balance of probabilities, shows that it's the case. That's nothing to do with copyright law specifically.