using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var list = Enumerable.Range(1,100).Select(i => new User{ Name = $"Name #{i%10}", Prop1 = i, Prop2 = 10*i, Prop3 = 100*i}).ToList();

        var dictionary = list.Select(item => new { Key = item.Name, Item = item}).GroupBy(e => e.Key).OrderBy(e => e.Key).ToDictionary(e => e.Key, e => e.ToList());

        foreach(var pair in dictionary)

        {

            var values = string.Join(", ", pair.Value.Select(e => e.ToString()));

            Console.WriteLine($"Key: {pair.Key}, Values: {values}");

        }

    }

}

​

public class User

{

    public string Name { get; set; }

    public int Prop1 { get; set; }

    public int Prop2 { get; set; }

    public int Prop3 { get; set; }

    public override string ToString() => $"{Prop1} {Prop2} {Prop3}";

}