Random.value unique?

Is each Random.value instance called within a single script uniquely generated? What about within a single "function"?

No unique results.

Each Random.value is a pseudo-random number, not a unique selection of a finite subset. They can (and in all likelihood eventually will) repeat, even if in a short-enough timeline it's likely that you won't get the exact real number twice out of Random.value.

If you want guaranteed unique values, you will probably want to use something like a Shuffle Bag, which The Lame Duck mentioned here.

For each time you call the random function it wil return a new number, it can of course return the same value as the previous call, but that would be totaly random ;) The random numbers are not TOTALY random but you won't see the difference when using it in a game.