Regex in java for finding duplicate consecutive words

I saw this as an answer for finding repeated words in a string. But when I use it, it thinks This and is are the same and deletes the is.

Regex

"\\b(\\w+)\\b\\s+\\1"

Any idea why this is happening?

Here is the code that I am using for duplicate removal

public static String RemoveDuplicateWords(String input)
{
    String originalText = input;
    String output = "";
    Pattern p = Pattern.compile("\b(\w+)\b\s+\b\1\b", Pattern.MULTILINE+Pattern.CASE_INSENSITIVE); 
    //Pattern p = Pattern.compile("\\b(\\w+)\\b\\s+\\1", Pattern.MULTILINE+Pattern.CASE_INSENSITIVE);
    Matcher m = p.matcher(input);
    if (!m.find())
        output = "No duplicates found, no changes made to data";
    else
    {
        while (m.find())
        {
            if (output == "")
                output = input.replaceFirst(m.group(), m.group(1));
            else
                output = output.replaceAll(m.group(), m.group(1));
        }
        input = output;
        m = p.matcher(input);
        while (m.find())
        {
            output = "";
            if (output == "")
                output = input.replaceAll(m.group(), m.group(1));
            else
                output = output.replaceAll(m.group(), m.group(1));
        }
    }
    return output;
}