Matt Cutts, answers a question about Multiple Breadcrumbs site structure in his latest Webmaster Help video where a user writes in to ask
Many of my items belong to multiple categories on my eCommerce site. Can I place multiple breadcrumbs on a page? Do they confuse Googlebot? Do you properly understand the logical site structure of my site?
If you have breadcrumbs on your webpage, Google will pick the first one, so according to Matt try to arrange all your web pages in the right hierarchy. However, if an item does belong to multiple categories, Matt suggests that you can use multiple breadcrumbs on a single web page. Under some circumstances having multiple breadcrumbs actually help Googlebot understand more about your site.
According to Matt Cutts, it is absolutely fine if you do not use multiple breadcrumbs, then there is nothing wrong in-fact most of the webmaster don’t do it. It is good to have one set of breadcrumb and encouraged by search engines.
If your pages are setup to belong to multiple categories, you can simply add more than one breadcrumb on a single web page. Google will pick the first by default, and will study the other breadcrumbs for deeper understanding of your site.
To hear Matt’s full response in his own words, please see the video below:
You can check the Google documentation about breadcrumb, which says “Pages can have more than one breadcrumb trail.”