I'm trying to add tags to a node through Examine.

I'm using the GatheringNodeDataEvent and looping through the tags on the node. Instead of just a comma seperated list, I would like to add each tag as its own value on a field.

In Lucene I would do like this:

foreach (var tagId in tagIds)
{
  var tag = new Node(Convert.ToInt32(tagId));
  d.Add(new Field("Tag", tag.Name, Field.Store.YES, Field.Index.ANALYZED, Field.TermVector.YES));
}

Where d i s my Lucene document. This works and adds several fields called Tag with different values on the document.

I've tried to do it like this:

foreach (var tagNode in tagNodes)
{
  e.Field.Fields.Add("tag", tagNode.GetProperty("title").Value);
}

This gives me the follwing error:
"An item with the same key has already been added."

Do anybody have an idea on how to accomplish this through Examine?