Remove duplicate strings - C#

Here is the code

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var words = new HashSet(); string text = "praveen kumar thalluri praveen kumar thalluri"; text = Regex.Replace(text, "\\w+", m => words.Add(m.Value.ToUpperInvariant())? m.Value: String.Empty);

Courtesy: http://stackoverflow.com/questions/1058783/regular-expression-to-find-and-remove-duplicate-words