SEO: 2 Navigation Menus

Question

I am building an e-commerce site and am wondering if having 2 identical navigation menus will hurt my SEO efforts.

I have a drop-down menu at the top of the page. That lists main categories, followed by sub-categories.

On my left navigation I have the same thing.

Both are structured like so:

<ul>
  <li><a href="#">Main Category 1</a>
    <ul>
      <li><a href="#">Sub Category</a></li>
      <li><a href="#">Sub Category</a></li>
      <li><a href="#">Sub Category</a></li>
    </ul>
  </li>
  <li><a href="#">Main Category 2</a>
    <ul>
      <li><a href="#">Sub Category</a></li>
      <li><a href="#">Sub Category</a></li>
      <li><a href="#">Sub Category</a></li>
    </ul>
  </li>
</ul>

The only difference is that I am using CSS to hide the main categories on the left navigation. Search engines will not be able to see this and will interpret it as an identical menu as the top menu.

Will this confuse the search engines? If so what if I just display sub-categories on the left menu without using CSS to hide the main categories?

Thanks in advance, JR

Answer 1

If anything you're doing only exists for the sake of bots, you might want to reconsider why you're really doing it. There are numerous resources that talk about what not to do in terms of SEO.