using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        var stringLine = "[{\"Item\": { \"Name\": \"item1\" }, \"ShipQuantity\": \" 50.0000000000000000000\", \"Total\": \"10.0000000000000000000\"},{\"Item\": { \"Name\": \"Gratuity\" }, \"ShipQuantity\": \" 1.0000000000000000000\", \"Total\": \"10.0000000000000000000\"}]";

        var unescapedstring = Regex.Unescape(stringLine);

        Console.WriteLine(unescapedstring);

​

    }

}