In this Google webmaster video, Matt Cutts discusses how Google handles multiple breadcrumbs on a page. Matt reveals that Google will actually only pick the first one to follow. Matt mentions that you should try to get pages in the correct category and hierarchy due to this particular issue.
Google states that you can have multiple breadcrumbs on a page, as it can in some cases help Googlebot find out more about the site, but keep in mind it will only follow the first one. So overall, it doesn’t hurt to have multiple breadcrumbs on a page for SEO. Instead, it can only help, unless, Google picks the first one to follow and that is not the breadcrumb you want to place emphasis on.
Yet another confusing answer by Google 🙂 Watch the video.