That’s interesting… Which page template are you using for the page where the [wp-catalogue] shortcode is embedded?
I can’t be 100% sure without seeing the theme code in more detail, but I think the problem is a conflict with the custom post type the WP Catalogue uses and your theme. To confirm, you could switch to the default theme temporarily, and see if the problem is still happening… If not, then it is definitely an issue between the theme and the plugin, and we can troubleshoot further from there.
I noticed that whats posting on the bottom is the product details of the last product listed on the page. So If I change the order I list my products that bottom post changes to show the product details of whatever the last product on the page is.
WP Catalogue is built on a custom post type. I suspect the conflict is simply that your theme is using something with the same name, and thus WordPress isn’t quite sure what to display on that page. Without access I can’t really help further. As it’s definitely a problem in your theme (rather than the plugin), this is something to take back to your developer or the theme vendor and get further assistance.