title: Custom Validation Attribute Multiple Times on same field
body: <p>How can I use Same Custom Validation Attribute Multiple Times on Same Field or simply enable AllowMultiple=true, for both server side and client side validation??</p>
  
  <p>I have a following Custom Validation Attribute:</p>
  
  <pre><code>[AttributeUsage(AttributeTargets.Field | AttributeTargets.Property, 
          AllowMultiple = true, Inherited = true)]
  public class RequiredIfAttribute : ValidationAttribute,IClientValidatable
  {
      public RequiredIfAttribute(string dependentProperties, 
       string dependentValues = "",
       string requiredValue = "val")
       {
       }
  }
  </code></pre>
  
  <p>Where in dependentProperties I can specify multiple dependant properties seperated by comma, in dependentValues I can specify for which values of dependant properties validation should process and finally in requiredValue I can specify expected value for the field to be validated.</p>
  
  <p>In my model there are two properties LandMark, PinCode and I want to use validation as follows:</p>
  
  <pre><code>public string LandMark { get; set; }
  [RequiredIf("LandMark","XYZ","500500")]
  [RequiredIf("LandMark", "ABC", "500505")]
  public string PinCode { get; set; }
  </code></pre>
  
  <p>The values here are just for example, as per it seems I can add the attribute multiple times and don't get any compile error, I have implemented TypeID in attribute and it works well from serverside if I remove client validation from it. But when I am implementing IClientValidatable on the attribute, it gives me an error:</p>
  
  <p>"Validation type names in unobtrusive client validation rules must be unique."</p>
  
  <p>Any help how can I solve it??</p>