为什么当我在列表mapsarray上循环时，它's向文本文件写入相同的2d int数组

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO;
using System.Drawing.Imaging;
namespace ConvertBitmapToArray
{
    public partial class Form1 : Form
    {
        List<string> MapsFiles = new List<string>();
        List<string> NumbersArray = new List<string>();
        int[,] ret;
        int index = 0;
        string f = "";
        string textfile = @"C:'Temp'Gimp Maps'Mapstest.txt";
        string text1;
        public Form1()
        {
            InitializeComponent();
            if (File.Exists(textfile))
            {
                File.Delete(textfile);
            }
            String[] allfiles = System.IO.Directory.GetFiles(@"C:'Temp'Gimp Maps'Bitmaps", "*.*");
            string text = File.ReadAllText(@"C:'Temp'Gimp Maps'CreateMaps1.txt");
            text1 = File.ReadAllText(@"C:'Temp'Gimp Maps'CreateMaps2.txt");
            string firstTag = "using";
            string lastTag = "class Level";
            index = text.IndexOf(firstTag, 0);
            int g = text.IndexOf(lastTag, index);
            f = text.Substring(index, g + 22);
            CreateArray(allfiles, "map");
        }
        private void CreateArray(String[] bitmaps, String MapName)
        {
            StreamWriter w = new StreamWriter(textfile, true);
            Bitmap bmp;
            List<int[,]> MapsArrays = new List<int[,]>();
            for (int i = 0; i < bitmaps.Length; i++)
            {
                bmp = new Bitmap(bitmaps[i]);
                ret = new int[bmp.Width, bmp.Height];
                int whiteColor = 0;
                int blackColor = 0;
                for (int x = 0; x < bmp.Width; x++)
                {
                    for (int y = 0; y < bmp.Height; y++)
                    {
                        Color color = bmp.GetPixel(x, y);
                        if (color.ToArgb() == Color.White.ToArgb())
                        {
                            whiteColor++;
                            ret[x, y] = 0;
                        }
                        else
                        {
                            blackColor++;
                            ret[x, y] = 1;
                        }
                    }
                }
                MapsArrays.Add(ret);
            }
            for (int i = 0; i < MapsArrays.Count; i++)
            {
                if (i == 0)
                {
                    w.WriteLine(f);
                    w.WriteLine("int[,] " + MapName + " = new int[,]");
                }
                else
                {
                    w.WriteLine("int[,] " + MapName + i + " = new int[,]");
                }
                w.WriteLine("{");
                for (int k = 0; k < MapsArrays[i].GetLength(0); k++)
                {
                    w.Write(" {");
                    for (int l = 0; l < MapsArrays[i].GetLength(1); l++)
                    {
                        var val = ret[k, l];
                        w.Write(val + ",");
                    }
                    w.Write("},");
                    w.WriteLine(string.Empty);
                }
                w.WriteLine("};");
                w.WriteLine(string.Empty);
            }
            w.WriteLine(text1);
            w.Close();
        }

在第一部分中，我正在循环位图文件，并将每个位图文件制作2d int数组，并将数组添加到List中所以在第一部分的末尾，mapsarray包含两个项目/索引，每个索引都有一个2d int数组。然后循环mapsarray。GetLength 0和1，并将值写入文本文件。

但是最后在文本文件中，我看到了相同的2d int数组:

int[,] map = new int[,]
{
 {0,0,0,1,1,1,1,0,},
 {0,0,0,1,0,0,1,0,},
 {0,0,0,1,1,0,1,0,},
 {1,1,0,0,1,0,1,0,},
 {0,1,0,0,1,0,1,0,},
 {0,1,1,1,1,0,1,0,},
 {0,0,0,1,1,0,1,1,},
 {0,0,0,0,0,0,0,0,},
};
int[,] map1 = new int[,]
{
 {0,0,0,1,1,1,1,0,},
 {0,0,0,1,0,0,1,0,},
 {0,0,0,1,1,0,1,0,},
 {1,1,0,0,1,0,1,0,},
 {0,1,0,0,1,0,1,0,},
 {0,1,1,1,1,0,1,0,},
 {0,0,0,1,1,0,1,1,},
 {0,0,0,0,0,0,0,0,},
};

我检查了一个断点MapsArrays包含两个项目，在每一个不同的2d int数组。那么为什么在文本文件中我得到相同的2d int数组?

我猜这部分有问题，我在这里做循环:

for (int k = 0; k < MapsArrays[i].GetLength(0); k++)
                {
                    w.Write(" {");
                    for (int l = 0; l < MapsArrays[i].GetLength(1); l++)
                    {