using System;
using System.Collections.Generic;
using System.Linq;
 
public class Test
{
 
        public static void Main()
        {
            string str = "1\t2\r\n3\t4";
        string[][] parsed = str
    .Split(new string[] {"\r\n"}, StringSplitOptions.None)
    .Select(s => s.Split('\t'))
    .ToArray();
    foreach(string[] arr in parsed)
        Console.WriteLine(string.Join(",",arr.Select(i => i.ToString()).ToArray()));
        }
}

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