using System;

using System.Collections.Generic;

using System.Linq;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        List<string> jsonResult = new List<string>();

            jsonResult.Add("{\n  \"arrayResult\": [\n    {\"Item1\": \"123\",\n    \"Item2\": \"858\",\n    \"Item3\": \"789\"\n    },\n    {\"Item1\": \"2588\",\n    \"Item2\": \"858\",\n    \"Item3\": \"587\"\n    }\n  ]\n}");

            jsonResult.Add("{\n  \"arrayResult\": [\n    {\"Item1\": \"123\",\n    \"Item2\": \"858\",\n    \"Item3\": \"789\"\n    },\n    {\"Item1\": \"2588\",\n    \"Item2\": \"858\",\n    \"Item3\": \"587\"\n    }\n  ]\n}");

            jsonResult.Add("{\n  \"arrayResult\": [\n    {\"Item1\": \"123\",\n    \"Item2\": \"858\",\n    \"Item3\": \"789\"\n    },\n    {\"Item1\": \"2588\",\n    \"Item2\": \"858\",\n    \"Item3\": \"587\"\n    }\n  ]\n}");

        List<JToken> items = jsonResult.Select(x => JObject.Parse(x))

            .SelectMany(x => x["arrayResult"])

            .ToList();

        dynamic result = new {

            arrayResult = items 

        };

        Console.WriteLine(JsonConvert.SerializeObject(result, new JsonSerializerSettings { Formatting = Formatting.Indented }));

    }

}