ExpandArray

using System;

namespace RotateArray
{
    class Program
    {
        static void Main(string[] args)
        {
            int[][] test = new int[][]{new int[]{4,5,6,7},
                                       new int[]{1,3,5,7},
                                       new int[]{9,5,4,2}};

            PrintArray(test);

            int[][] result = ExpandArray(test);

            PrintArray(result);

            Console.ReadLine();
        }

        public static int[][] ExpandArray(int[][] input)
        {
            int[][] result = new int[input.Length * 2][];
            for (int y1 = 0, y2 = 0; y1 < input.Length; y1++, y2 += 2)
            {
                result[y2] = new int[input[y1].Length * 2];
                for (int x1 = 0, x2 = 0; x1 < input[y1].Length; x1++, x2 += 2)
                    result[y2][x2 + 1] = (result[y2][x2] = input[y1][x1]);
                result[y2 + 1] = (int[])result[y2].Clone();
            }
            return result;
        }

        private static void PrintArray(int[][] input)
        {
            for (int y = 0; y < input.Length; y++)
            {
                for (int x = 0; x < input[y].Length; x++)
                    Console.Write(input[y][x] + ",");
                Console.WriteLine();
            }
        }
    }
}