Does Mathf.PerlinNoise() always return the same output?

I'm going to do something like in this video to generate a handfull of random islands: https://www.youtube.com/watch?v=COmtTyLCd6I

My Concern is that it won't come out identical every time on every platform. Basically once the islands are generated, I'm going to put static buildings and NPCs on top of it. So if the Perlin Noise generator has a different result on say OSX, then the buildings and NPCs will all get pushed around or end up underground. Not that I can't create meshes in like blender and import them, but I figured it would be a clever way to reduce my game's size.

So basically I recall that System.Random can change based on the OS, for example if I do this on x64 Windows:

  Update(){
     System.Random prng = new System.Random(seed);
                                //These values are made up
    Debug.Log(prng.Next(0,10)); //returns 6 every time
    Debug.Log(prng.Next(0,10)); //returns 2 every time
    Debug.Log(prng.Next(0,10)); //returns 5 every time
    Debug.Log(prng.Next(0,10)); //returns 7 every time
    Debug.Log(prng.Next(0,10)); //returns 2 every time
    Debug.Log(prng.Next(0,10)); //returns 1 every time
  }

Doesn't mean I'll get the same values on say x32 Windows, or on Android.

What I'm wondering is if Perlin Noise values be the same every time regardless of system/os/processor?