How display two columns in Mvc WebGrid with single object

I am new to MVC and I want to display name of a user in two columns in a WebGrid as display below.

Currently the web grid display data in below format.

User 1

User 2

User 3

User 4

I am binding my WebGrid with List, list contains username.

My Controller

public ActionResult Index()

{

List userList = new List();

userList.Add("User1");

userList.Add("User2");

userList.Add("User3");

userList.Add("User4");

return View(userList);

}

My Cshtml

enter code here

@using (Html.BeginForm())

{

var grid = new WebGrid(Model);

@grid.GetHtml(columns: grid.Columns(grid.Column(format: (item) => item)));

}