Duplicate sections on checkout

I've searched the forum and haven't seen any posts dealing with the problem we're coming up against.

On the checkout page there are duplicates of all the sections - two shopping cart contents, two discount coupons, two delivery information, two payment information, two comment boxes - and just one submit button.

The site uses several mods including Fast & Easy Checkout, Ultimate SEO and Multisite.

I've posted in the forums for those mods but I'm not sure I can narrow it down to any one of them - or the default Zen install.

Can anyone offer any suggestions on what's causing this to happen? Thanks!

Sounds like you've likely got extra backup copies of files left on your server as a result of renaming files but keeping the .php extension on the filenames. ie: renaming header_php.php to header_php_old.php instead of something more appropriate like header_php.old

You can find all the modified files and all the "extra" files on your site by using a comparison tool like WinMerge, similar to the concept described here: http://www.zen-cart.com/wiki/index.php/Troubleshoot_-_Diagnosing_Obscure_Issues

Or, maybe you've installed one or more addons incorrectly and you're causing it to do things multiple times.