Form1.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Windows.Forms;

namespace testapp
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
    
        //удалить повторы 
        private void button1_Click(object sender, EventArgs e)
        {
            string[] myArray = textBox1.Text.Split(new Char[] { ',' });
            List<String> names = myArray.OfType<String>().ToList();
            List<String> noDupes = names.Distinct().ToList();
            textBox1.Text = displayMembers(noDupes);
        
       }
        //Отобразить 
        public string displayMembers(List<String> noDupes)
        {
            return string.Join("\n ", noDupes.ToArray());

        }
        //spravka
        private void button2_Click(object sender, EventArgs e)
        {
            MessageBox.Show(" Пример \n  \n  Имя Фамилия 10а, \n  Имя Фамилия 11б, \n  Имя Фамилия 11a, \n  Имя Фамилия 11а, ");

        }

        //form laod
        private void Form1_Load(object sender, EventArgs e)
        {

            textBox1.Multiline = true;

            textBox1.ShortcutsEnabled = true;

            textBox1.ScrollBars = ScrollBars.Vertical;
            textBox1.AcceptsReturn = true;
            textBox1.AcceptsTab = true;
            textBox1.WordWrap = true;
                   
            // Set the default text of the control.
            textBox1.Text = "Имя Фамилия,";
          
        }

        //ctrls
        protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
        {
            const int WM_KEYDOWN = 0x100;
            var keyCode = (Keys)(msg.WParam.ToInt32() &
                                  Convert.ToInt32(Keys.KeyCode));
            if ((msg.Msg == WM_KEYDOWN && keyCode == Keys.A)
                && (ModifierKeys == Keys.Control)
                && textBox1.Focused)
            {
                textBox1.SelectAll();
                return true;
            }
            return base.ProcessCmdKey(ref msg, keyData);
        }



        //ToolStripMenuItem
        private void открытьToolStripMenuItem_Click_1(object sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
                openFileDialog1.Filter = "Text Files (.txt)|*.txt|All Files (*.*)|*.*";
                openFileDialog1.FilterIndex = 1;
                System.IO.StreamReader sr = new
                System.IO.StreamReader(openFileDialog1.FileName, System.Text.Encoding.GetEncoding(1251), true);
                textBox1.Text = sr.ReadToEnd();
                sr.Close();

            }
        }
        //save as
        private void сохранитьКакToolStripMenuItem_Click(object sender, EventArgs e)
        {

            
                using (var sfd = new SaveFileDialog())
                {
                    sfd.Filter = "txt files (*.txt)|*.txt";
                    sfd.FilterIndex = 2;

                    if (sfd.ShowDialog() == DialogResult.OK)
                    {
                        File.WriteAllText(sfd.FileName, textBox1.Text);
                    }
                }
            
        }



      }
    }