using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        List<uint> list = new List<uint> { 1,1,1,2,3,4,4 };

​

        var duplicates = list.GroupBy(x => x).Select(y => new { Nummer = y.Key, Count = y.Count() }).ToList();

        for(int i=0; i<duplicates.Count; i++)

        {

            Console.WriteLine(duplicates[i]);

        }

​

    }

}