When built with Visual Studio 2012 for .NET 4.0, produces different results between all of .NET x86, .NET x64 and mono x86 on Windows. Tested on an i7-3820

gistfile1.cs

using System;
using System.Runtime.InteropServices;
namespace randomtest
{
    class Program
    {
        static void Main(string[] args)
        {
            randomtest.Random random = new randomtest.Random(0);
            for (int i = 0; i < 10000; i++)
            {
                float valX = (float)random.NextDouble();
                float valY = (float)random.NextDouble();
                float normalizedX;
                float normalizedY;
                Normalize(valX, valY, out normalizedX, out normalizedY);
                float result = DoCalc(normalizedX, normalizedY);

                Console.WriteLine(result.ToString("G9", System.Globalization.CultureInfo.InvariantCulture));
            }
        }
        static float DoCalc(float x, float y)
        {
            float direction = (float)Math.Atan2(y, x);

            direction -= 1f / 30f;

            float dirY = (float)Math.Sin(direction);
            return dirY;
        }


        public static float DistanceSquared(float value1X, float value1Y)
        {
            return value1X * value1X + value1Y * value1Y;
        }

        public static void Normalize(float valueX, float valueY, out float resultX, out float resultY)
        {
            float factor = DistanceSquared(valueX, valueY);

            if (factor == 0)
            {
                resultX = 0f;
                resultY = 0f;
                return;
            }
            factor = 1f / (float)Math.Sqrt(factor);
            resultX = valueX * factor;
            resultY = valueY * factor;
        }
    }

    // Mono random
    public class Random : System.Random
    {

        const int MBIG = int.MaxValue;
        const int MSEED = 161803398;

        int inext, inextp;
        int[] SeedArray = new int[56];

        public Random(int Seed)
        {
            int ii;
            int mj, mk;

            // Numerical Recipes in C online @ http://www.library.cornell.edu/nr/bookcpdf/c7-1.pdf

            // Math.Abs throws on Int32.MinValue, so we need to work around that case.
            // Fixes: 605797
            if (Seed == System.Int32.MinValue)
                mj = MSEED - System.Math.Abs(System.Int32.MinValue + 1);
            else
                mj = MSEED - System.Math.Abs(Seed);

            SeedArray[55] = mj;
            mk = 1;
            for (int i = 1; i < 55; i++)
            {  //  [1, 55] is special (Knuth)
                ii = (21 * i) % 55;
                SeedArray[ii] = mk;
                mk = mj - mk;
                if (mk < 0)
                    mk += MBIG;
                mj = SeedArray[ii];
            }
            for (int k = 1; k < 5; k++)
            {
                for (int i = 1; i < 56; i++)
                {
                    SeedArray[i] -= SeedArray[1 + (i + 30) % 55];
                    if (SeedArray[i] < 0)
                        SeedArray[i] += MBIG;
                }
            }
            inext = 0;
            inextp = 31;
        }

        protected override double Sample()
        {
            int retVal;

            if (++inext >= 56) inext = 1;
            if (++inextp >= 56) inextp = 1;

            retVal = SeedArray[inext] - SeedArray[inextp];

            if (retVal < 0)
                retVal += MBIG;

            SeedArray[inext] = retVal;

            return retVal * (1.0 / MBIG);
        }
    }
}