How to keep the old text and add a new line of text if you type in a command

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C#

Unity3D

Hi, I am basically trying to keep the old text and while if you type in help it add a new line of text. the problem is the every time I type in help it prints the old text again (twice) and then prints the new text.

public Canvas myCanvas;
public Text myText;

private string display = "";

List<string> chatEvents;

private bool calltext;

public InputField inputfield;
private Dictionary<string, System.Action<string,string>> commands;

protected void Awake()
{
    commands = new Dictionary<string, System.Action<string,string>>();
    // Add the commands you want to recognise along with the functions to call
    commands.Add( "help", OnHelpTyped );
    // Listen when the inputfield is validated
    inputfield.onEndEdit.AddListener( OnEndEdit );
}

private void OnEndEdit( string input )
{
    // Only consider onEndEdit if the Submit button has been pressed
    if ( !Input.GetButtonDown( "Submit" ) )
        return;

    bool commandFound = false;

    // Find the command
    foreach ( var item in commands )
    {
        if ( item.Key.ToLower().StartsWith( input.ToLower() ) )
        {
            commandFound = true;
            item.Value( item.Key, input );
            break;
        }
    }

    // Do something if the command has not been found
    if ( !commandFound )
        Debug.Log( "No word found" );

    // Clear the input field (if you want)
    inputfield.text = "";
}

private void OnHelpTyped( string command, string input )
{
    chatEvents.Add ("The List");
    calltext = true;
}

// Use this for initialization
void Start () {
    chatEvents = new List<string>();

    chatEvents.Add("Welcome to my simple application ");
    chatEvents.Add ("Type help for list of commands");

    calltext = true;

}

// Update is called once per frame
void Update () {
    if(calltext)
    {
        AddText();
        calltext = false;
    }
}

void AddText()
{
    foreach(string msg in chatEvents)
    {
        display = display.ToString () + msg.ToString() + "\n";
    }
    myText.text = display;
}

What I have tried:

I have tried everything and it seems to work, but it adds the last two text plus the new text