Regular Expression For Duplicate Words

I believe this regex handles more situations:

/(\b\S+\b)\s+\b\1\b/

A good selection of test strings can be found here: http://callumacrae.github.com/regex-tuesday/challenge1.html

Try this regular expression:

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

Here \b is a word boundary and \1 references the captured match of the first group.

Regex101 example here