Q:

Regex: match when string has repeated letter pattern

I'm using the Regex interpreter found in XYplorer file browser.  I want to match any string (in this case a filename) that has repeated groups of 'several' characters.  More specifically, I want a match on the string:
 jack johnny - mary joe ken johnny bill

because it has 'johnny' at least twice.  Note that it has spaces and a dash too.
It would be nice to be able to specify the length of the group to match, but in general 4, 5 or 6 will do.
I have looked at several previous questions here, but either they are for specific patterns or involve some language as well.  The one that almost worked is:
RegEx: words with two letters repeated twice (eg. ABpoiuyAB, xnvXYlsdjsdXYmsd)
where the answer was:
\b\w*(\w{2})\w*\1

However, this fails when there are spaces in the strings.
I'd also like to limit my searches to .jpg files, but XYplorer has a built-in filter to only look at image files so that isn't so important to me here. 
Any help will be appreciated, thanks.
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EDIT - 
The regex by OnlineCop below answered my original question, thanks very much:
(\b\w+.\b).(\1)
I see that it matches words, not arbitrary string chunks, but that works for my present need.  And I am not interested in capturing anything, just in detecting a match.
As a refinement, I wonder if it can be changed or extended to allow me to specify the length of words (or string chunks) that must be the same in order to declare a match.  So, if I specified a match length of 5 and my filenames are:
1)  jack john peter paul mary johnnie.jpg
2)  jack johnnie peter paul mary johnnie.jpg
the first one would not match since no substring of five characters or more is repeated.  The second one would match since 'johnnie' is repeated and is more than 5 chars long.

A:

Do you wish to capture the word 'johnny' or the stuff between them (or both)?
This example shows that it selects everything from the first 'johnny' to the last, but it does not capture the stuff between:
Re:  (\b\w+\b).*(\1)
Result:  jack  bill

This example allows some whitespace between names/words:
Re: (\b\w+.*\b).*(\1)
String: Jackie Chan fought The Dragon who was fighting Jackie Chan
Result: Jackie Chan Jackie Chan

