using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        List<Model> input = new List<Model>

        {

            new Model { Id = 1,  Description = "Desc1", Status = 1 },

            new Model { Id = 2,  Description = "Desc2", Status = 2 },

            new Model { Id = 1,  Description = "Desc3", Status = 2  }, 

            new Model { Id = 3,  Description = "Desc4", Status = 1 },

            new Model { Id = 3,  Description = "Desc5", Status = 2  },

        };

        var result = input.GroupBy(x => x.Id)

            .Select(x => new

                    {

                        Id = x.Key,

                        Description = x.Select(y => y.Description).ToList()

                    })

            .ToList();

        // Or

        /*

        var result = (from x in input

                      group x by x.Id into g

                      select new

                      {

                          Id = g.Key,

                          Description = g.Select(y => y.Description).ToList()

                      }

            ).ToList();

        */

        foreach (var item in result)

        {

            Console.WriteLine($"Id: {item.Id}");

            Console.WriteLine($"Description: {String.Join(",", item.Description)}");

        }

    }

}

​

public class Model

{

    public int Id { get; set; }

    public string Description { get; set; }

    public int Status { get; set; }

}