More than one rel=canonical on a page

What is wrong

When a single webpage contains more than one rel=canonical tag, search engines receive conflicting instructions about which version of the page should be treated as the original. The rel=canonical tag is meant to tell Google which URL is the authoritative version when duplicate or similar content exists across your site. Multiple tags on one page create confusion because the engine cannot determine which instruction to follow.

Why it costs you

This confusion means Google may not index the page you want indexed, or it may waste time processing conflicting signals instead of crawling other important pages on your site. Visitors might also land on a version of the page you didn't intend to be the main one, and any SEO value the page has built up can be split between multiple URLs rather than concentrated on a single one.

How to fix it

Each page should contain only 1 rel=canonical tag. Check your page templates and the individual page code to find where the duplicate tags are being added. Common causes are a canonical tag in the header template plus another one added manually to a specific page, or multiple canonical tags being inserted by plugins or content management system settings. Remove all but the one that points to the URL you actually want to rank.