AllowMultiple does not work with Property Attributes?

I'm tying to collect all Custom Attributes placed over a Property. There are more than one Attributes of the same type assigned to the Property, but when collecting them , the resulting collection only contains the first Attribute of the specific type:

The Attribute class

[AttributeUsage(System.AttributeTargets.Property,
               AllowMultiple = true)]

public class ConditionAttribute : Attribute{...}

Usage:

[ConditionAttribute("Test1")]
[ConditionAttribute("Test2")]
[ConditionAttribute("Test3")]
public Color BackColor{get; set;}

Now when looping through all Props of the object 'value' whose class contains the Prop "BackColor":

foreach (PropertyDescriptor property in TypeDescriptor.GetProperties(value))
{
  foreach (Attribute attribute in property.Attributes)
  {   ... }
   ....
}

the collection property.Attributes only contains ONE Attribute of type "ConditionAttribute" : The one with "Test1". The others are ignored;-(

So does AllowMultiple not work for Property Attributes ?

Thanks in advance

henrik