保存表单抛出异常[参数异常" Item with Same Key has been added "]

我正在尝试创建一个更新用户信息的表单。我正在使用类型视图的模型类用户:

public class User : MembershipUser, IEntity
    {
        public virtual int Id { get; set; }
        public virtual string Username { get; set; }
        public virtual string Password { get; set; }
        public virtual string Name { get; set; }
        public virtual string Surname { get; set; }
        public virtual Role Role { get; set; }
        public virtual string ProfileImage { get; set; }
        public virtual string About { get; set; }
    }

视图如下所示:

using (Html.BeginForm("SaveUser", "BlogUser", FormMethod.Post, new { @class = "form-horizontal", enctype = "multipart/form-data" }))
{
    <div class="form-group">
        @Html.HiddenFor(x => x.Id)
        @Html.HiddenFor(x => x.ProfileImage)
        @Html.HiddenFor(x => x.UserName)
        @Html.HiddenFor(x => x.Password)
        @Html.HiddenFor(x => x.Role)
        <div class="col-sm-10">
            <label>Jméno</label>
        </div>
        <div class="col-sm-10">
            @Html.TextBoxFor(x => x.Name, new { @class = "form-control" })
            @Html.ValidationMessageFor(x => x.Name)
        </div>
    </div>
    <div class="form-group">
        <div class="col-sm-10">
            <label>Příjmení</label>
        </div>
        <div class="col-sm-10">
            @Html.TextBoxFor(x => x.Surname, new { @class = "form-control" })
            @Html.ValidationMessageFor(x => x.Surname)
        </div>
    </div>
    <div class="form-group">
        <div class="col-sm-10">
            <label>Profilový obrázek</label>
        </div>
        <div class="col-sm-10">
            <input type="file" name="picture" />
            @if (!String.IsNullOrEmpty(Model.ProfileImage))
                {
                <img src="@Url.Content("~/Upload/UserImages/" + Model.ProfileImage)" />
            }
        </div>
    </div>
        <div class="form-group">
            <div class="col-sm-10">
                <label>Něco o mně</label>
            </div>
            <div class="col-sm-10">
                @Html.TextAreaFor(x => x.About, new { @class = "form-control formatedText", @rows = 20 })
                @Html.ValidationMessageFor(x => x.About)
            </div>
        </div>
            <div class="form-group">
                <div class="col-sm-10">
                    <button type="submit" class="btn btn-primary btn-lg btn-block">Uložit</button>
                </div>
            </div>
}

我得到正确的用户，我已经预先填写了正确的详细信息列，但提交后它抛出异常[参数异常"具有相同键的项目已被添加"]。我甚至不会触发SaveUser()控制器方法，所以我至少可以调试它。我不知道问题出在哪里。你能帮我吗?