NotEqual Fluent Validation validator with client side validation

Adapter.js

(function ($) {
    $.validator.addMethod("notequal", function (value, element, param) {
        return this.optional(element) || value != $(param).val();
    }, "This has to be different...");

    $.validator.unobtrusive.adapters.add("notequal", ["field"], function (options) {
        options.rules["notequal"] = options.params.field;
        if (options.message) options.messages["notequal"] = options.message;
    });
})(jQuery);  

Global.asax.cs

FluentValidationModelValidatorProvider.Configure(provider =>
{
    provider.Add(typeof(NotEqualValidator), (metadata, context, description, validator) => new NotEqualPropertyValidator(metadata, context, description, validator));
});

index.cshtml

@model Test.Models.PersonModel
@using (Html.BeginForm())
{
    @Html.TextBoxFor(x => x.First)
    @Html.ValidationMessageFor(x => x.First)
    @Html.TextBoxFor(x => x.Last)
    @Html.ValidationMessageFor(x => x.Last)
    <button type="submit">OK</button>
}

PersonModel.cs

[Validator(typeof(PersonValidator))]
public class PersonModel
{
    public string First { get; set; }
    public string Last { get; set; }
}
public class PersonValidator : AbstractValidator<PersonModel>
{
    public PersonValidator()
    {
        RuleFor(x => x.First).NotEqual(x => x.Last);
    }
}

PropertyValidator.cs

public class NotEqualPropertyValidator : FluentValidationPropertyValidator
{

    public NotEqualPropertyValidator(ModelMetadata metadata, ControllerContext controllerContext, PropertyRule rule, IPropertyValidator validator)
        : base(metadata, controllerContext, rule, validator)
    {
    }

    public override IEnumerable<ModelClientValidationRule> GetClientValidationRules()
    {
        if (!ShouldGenerateClientSideRules()) yield break;

        var formatter = new MessageFormatter().AppendPropertyName(Rule.PropertyName);
        string message = formatter.BuildMessage(Validator.ErrorMessageSource.GetString());
        var rule = new ModelClientValidationRule
        {
            ValidationType = "notequal",
            ErrorMessage = message
        };
        rule.ValidationParameters["field"] = String.Format("#{0}", ((NotEqualValidator)Validator).MemberToCompare.Name);
        yield return rule;
    }
}