In nature every thing is unique, no two leaves are identical, even of the same tree. Every person is unique. https://youtu.be/5PWT78_VfDo?t=4m41s
It looks like only man made things are identical. And that too for a purpose like standardizations are put, so that parts can be replaced. Most of the things are mechanical and physical.
Mass production also produces identical copies in large number. But recently Elon Musk company when creating tiles they have not create same identical tiles. For dimentions and fit they are same standard dimentions. But for look they employed unique output. https://youtu.be/-mUJnKI3ipI?t=9m40s
All the things that are produced by machine are identical. But its hard for hand made things to be exact identical. With pricision in process there is no uniqueness in output. With randomness in the process there is uniqueness in output.
So in the industry you have these cookie cutters, let's call them a signal which is always identical, what if we add some noise to it to make the output meaningfully unique.