Defining "essentially the same" sounds hard, especially if a series of "small" changes happen over a period of time. Ship of Theseus, anyone?
As soon as you try defining "small changes" and the period of time on which they can occur, it is arguably a problem that will lead to loopholes easily abused by the legal departments of any big corp.
Defining "essentially the same" sounds hard, especially if a series of "small" changes happen over a period of time. Ship of Theseus, anyone?