Todd,
When you access www.pitchcare.com/shop/moss-control/ it will show you the exact content if you go to www.pitchcare.com/shop/moss-control/index.html.
Google See these two URL as 2 different URLs with same content, hence your content is duplicated
this is an article of how to deal with DC from Google Blog http://googlewebmastercentral.blogspot.com/2006/12/deftly-dealing-with-duplicate-content.html
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