Add Duplicates keys to NameValueCollection

Question

I have read that NameValueCollection allows for duplicate keys to be added, however this does not seem to be the case when I try to use it.

My Code

using (var wb = new WebClient())
{
     var data = new NameValueCollection();
     var sourceData = (List<Dictionary<string, object>>)dic["mapData"];
     var countSource = sourceData.Count;

     foreach (var item in (List<Dictionary<string, object>>)dic["mapData"])
     {
          data.Add("pp", item["Latitude"].ToString() + "," + item["Longitude"].ToString());
     }

     var dataCount = data.Count;
     var response = wb.UploadValues(@"http://dev.virtualearth.net/REST/V1/Imagery/Map/road/?mapArea=" + swLat.ToString() + "," + swLong + "," + neLat + "," + neLong + "&mapSize=800,600&key=" + key, "POST", data);

     return this.LargeJson(new { imageData = CreateBase64Image(response) });
}

What I am observing

my sourceData contains 36 items

I am iterating through sourceData and adding items to my NameValueCollection data and add items with the same key "pp"

I was expecting to have 36 items in my data NameValueCollection, but I am only getting 1 and all of my values get appended to the same key.

What am I missing ?

Answer 1

This is the expected behaviour - see the documentation:

If the specified key already exists in the target NameValueCollection instance, the specified value is added to the existing comma-separated list of values in the form "value1,value2,value3". The values are associated with the same key in the target NameValueCollection instance.