using System.Collections.Generic;
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]);