using System;

using System.Collections.Generic;

using System.Linq;

using Newtonsoft.Json;

​

public class Program

{

    public static void Main()

    {

        var objectA = new Example { 

            First = "First"

        };

        var objectB = new Example { 

            First = "First"

        };

        var unionedCombo = new List<Example> { objectA }.Union(new List<Example> { objectB});

        foreach(var item in unionedCombo) { 

            Console.WriteLine(JsonConvert.SerializeObject(item));   

        }

        string a = "First";

        string b = "First";

        var unionedComboStrings = new List<string> { a }.Union(new List<string> { b });

        foreach(var item in unionedComboStrings) { 

            Console.WriteLine(item);    

        }

    }

}

​

public class Example { 

    public string First { get; set; }

    public string Second { get; set; }

}