歧义错误

这是我的代码

 HotelMGT _DB = new HotelMGT();
    public virtual ActionResult Index()
    {
        ViewBag.TypeID = new string[] { "Assets", "Liabilities", "Income","Expenses" };
        var model = from r in _DB.AccountHead
                    orderby r.AccountHeadID ascending
                    //where r.AccountTypeID == AccountTypeID || (AccountTypeID==null)
                    select r; //_DB.AccountType;
        return View(model );
    }

我收到以下错误。

 Ambiguity between 'MyHotel.Models.HotelMGT.AccountHead' and   
 'MyHotel.Models.HotelMGT.AccountHead'

识别与 C# 或 MVC 相关的错误，我该如何解决这个问题？欢迎所有建议。

问候。