It appears that if you are in a top level page and press "Place An Ad", you use the uploadproduct.php regardless as to which catagory you are placing the ad in. If you go to a catagory, and press "Place and Ad", you use the uploadproduct2.php or whatever no. applies.
I think regardless as to where you upload from, it should use the specific number for the catagory choosen.
Hope I have something wrong...