using System;
using System.Text.RegularExpressions;
public class Test
{
    public static void Main()
    {   
        string text = @"John, Doe, ""Sid, Nency"", Smith";
        string[] pieces1 = Regex.Split(text, @",(?=([^""]*""[^""]*"")*[^""]*$)");
        string[] pieces2 = Regex.Split(text, @",(?=(?:[^""]*""[^""]*"")*[^""]*$)");
        Console.WriteLine("First:");
        foreach (string piece in pieces1)
        {
            Console.WriteLine(piece);
        }
        Console.WriteLine("Second:");
        foreach (string piece in pieces2)
        {
            Console.WriteLine(piece);
        }
    }
}