Duplicate Items in category list

Currently, we have 1.3.5 installed with the same version database patches, we are experiencing duplicate items in one category only. I have searched the database over trying to find a duplicate record to no avail. Any ideas would be much appreciated. I have included a URL to the store below, the category with duplicated items is "books".

http://www.emovieposter.com/shop/

Thanks in advance

Ok, the duplicates were found in every category. Turns out, that the specials cause duplicates to display when you have an item that has more than one special in the specials table. This can be fixed by adding the appropriate GROUP BY clause to your mysql query that pulls the items for the main item viewer.

the file is /includes/index_filters/default_filter.php

And you need to add a

GROUP BY p.products_id 

before the

 $alpha_sort

At the end of your queries.

I am also having the same problem - I see by using Crimson Editor that "$alpha_sort" is listed 6 times in the mentioned file. You state to do this at the end of your queries, I am a little confused if I should add the code before the first two area where "$alpha_sort" appears or the four times below where "and p...." is listed in the file default_filter.php.

Thanks