gistfile1.cs

internal class Program
    {
        // Sample unordered list of strings 
        private const string OriginalString = "[V],[E],[B],[B],[O],[E],[P],[B]";

        private static void Main(string[] args)
        {
            var lst = new List<string>();
            lst.AddRange(OriginalString.Split(','));

            // Getting duplicate entries from the unordered list
            var duplicates = lst.GetDuplicates();

            // Check if the List<string> extension method works
            if (duplicates.Count > 0)
            {
                Assert.AreEqual(2, duplicates.Count);
                Assert.IsTrue(duplicates.Contains("[E]"));
                Assert.IsTrue(duplicates.Contains("[B]"));
            }
            else
            {
                Assert.AreEqual(0, duplicates.Count);
            }
        }
    }