Product showing up twice in category

The same product is showing up twice in a category. Here's the link to the category:

http://www.robmcintosh.ca/index.php?main_page=index&cPath=72_297_790

The "ODESSA GOLD COVERED SUGAR" is showing up twice - same Product ID and everything. Is this a bug in ZC1.5? I attached a screenshot of the admin view, the product is only there once.

Hard to say what's causing it.

But since the problem doesn't appear to occur (I can't seem to make it happen) in a fresh clean install of Zen Cart without any mods which alter the category/product listings, and yours has numerous such alterations, I'm guessing the problem is in those alterations (such as a bad SQL query). Or maybe there's a problem in your database data (external importing tools that have added multiple entries of the product in the selected category/categories perhaps?), etc.