String comparer pulled from http://www.catalysoft.com/articles/StrikeAMatch.html and converted to C#. Wrote many years ago for a job.

FuzzyStringComparer.cs

namespace Poop
{
    public class FuzzyStringComparer
    {
        /// <summary>Computes lexical similarity of two strings, case insensitive.</summary>
        /// <returns>Lexical similarity value in the range [0,1].</returns>
        /// <remarks>http://www.catalysoft.com/articles/StrikeAMatch.html</remarks>
        public static double CompareLexical(this string str1, string str2)
        {
            if (str1 == str2)
                return 1;
            if (str1.Length == 1 || str2.Length == 1)
                return 0;
            else
            {
                var pairs1 = wordLetterPairs(str1.ToUpper());
                var pairs2 = wordLetterPairs(str2.ToUpper());
                int intersection = 0;
                int union = pairs1.Count + pairs2.Count;
                for (int i = 0; i < pairs1.Count; i++)
                {
                    object pair1 = pairs1[i];
                    for (int j = 0; j < pairs2.Count; j++)
                    {
                        object pair2 = pairs2[j];
                        if (pair1.Equals(pair2))
                        {
                            intersection++;
                            pairs2.RemoveAt(j);
                            break;
                        }
                    }
                }
                return (2.0 * intersection) / union;
            }
        }
        public static double NameSimilarityThreshold = .6;
        
        /** @return an array of adjacent letter pairs contained in the input string */
        private static string[] letterPairs(string str)
        {
            int numPairs = Math.Max(0, str.Length - 1);
            string[] pairs = new string[numPairs];
            for (int i = 0; i < numPairs; i++)
            {
                pairs[i] = str.Substring(i, 2);
            }
            return pairs;
        }
        
        /** @return an ArrayList of 2-character Strings. */
        private static IList<string> wordLetterPairs(string str)
        {
            var allPairs = new List<string>();
            // Tokenize the string and put the tokens/words into an array
            string[] words = Regex.Split(str, "\\s");
            // For each word
            for (int w = 0; w < words.Length; w++)
            {
                // Find the pairs of characters
                string[] pairsInWord = letterPairs(words[w]);
                for (int p = 0; p < pairsInWord.Length; p++)
                {
                    allPairs.Add(pairsInWord[p]);
                }
            }
            return allPairs;
        }
    }
}