Niccol, i have played around with both product_listing.php, and tpl_modules_product_listing.php and still can not get the image to appear. I think it might work if I can add an extra field definition for the additional image in this block of code from product_listing.php. However I've tried several times and don't know how exactly to write the code. Let me know if you have a suggestion.
PHP Code:
if (isset($_GET['manufacturers_id'])) {
$lc_text = '<a href="' . zen_href_link(zen_get_info_page($listing->fields['products_id']), 'cPath=' . (($_GET['manufacturers_id'] > 0 and $_GET['filter_id']) > 0 ? zen_get_generated_category_path_rev($_GET['filter_id']) : ($_GET['cPath'] > 0 ? zen_get_generated_category_path_rev($_GET['cPath']) : zen_get_generated_category_path_rev($listing->fields['master_categories_id']))) . '&products_id=' . $listing->fields['products_id']) . '">' . zen_image(DIR_WS_IMAGES . $listing->fields['products_image'], $listing->fields['products_name'], IMAGE_PRODUCT_LISTING_WIDTH, IMAGE_PRODUCT_LISTING_HEIGHT, 'class="listingProductImage"') . '</a>';
Also,
Why not edit the two images together in a graphics program? Then they would both be displayed.
the idea behind displaying the front(default) and back(additional) images side by side is to make it easy for the client to upload new products to the shopping cart, and to keep the image system clean.