OSCommerce

We have upgraded our OSCommerce eshop to PHP5 and for some reason we now get each product several times with a different price. The main categories show the right amount of products but when looking at the page that displays the products for purchase you suddenly have one product several hundred times and with different prices. The database information is correct and only includes each product once and with the correct price. If you know what the problem is and how to fix it. please bid on this project. Only experienced coders please.