Canonical tags, or rel=”canonical”, are HTML elements used to tell search engines like Google which version of a page is the preferred one when there are duplicates. This helps avoid issues with duplicate content, ensuring search engines index the right page and consolidate ranking signals.

Can Multiple Canonical Tags Cause SEO Issues?

Yes, having multiple canonical tags on a page can likely cause SEO problems. Research suggests that search engines may only process the first tag they find, ignoring others, which can lead to confusion. This might result in the wrong page being indexed, diluted link equity, or even crawl errors, all of which can harm your site’s visibility in search results.

Why This Happens

If multiple tags point to different URLs, search engines might struggle to decide which page is the “master” copy, splitting the authority between pages. This is especially risky if technical errors, like CMS plugins adding extra tags, create conflicting signals.

How to Fix It

To avoid issues, ensure each page has only one canonical tag in the section, pointing to the preferred URL. Use tools like Google Search Console or Ahrefs Site Audit to detect and fix multiple tags. If conflicts arise, consider server-side redirects to enforce a single canonical URL.

Understanding Canonical Tags and Their Role in SEO

These tags are HTML elements placed in the section of a webpage to specify the preferred version of a page when multiple URLs contain identical or similar content. For example, if a page is accessible via example.com/page and example.com/page?sort=price, a canonical tag can indicate which URL should be indexed by search engines like Google. This helps consolidate link equity, improve rankings, and prevent duplicate content issues, which can dilute SEO efforts across multiple pages.

According to Moz’s guide on canonicalization, published on April 4, 2025, canonical tags are essential for directing search engines to treat certain pages as duplicates and index only the preferred version. This is particularly important for modern websites using content management systems (CMS) that may generate multiple URLs for the same content, such as through sorting, filtering, or tracking parameters.

Why Multiple Canonical Tags Cause Issues: A Technical Perspective

The underlying reason for these issues is that canonical tags are treated as suggestions, not directives, by search engines. Google’s documentation, as seen in Google Search Central’s guide on consolidating duplicate URLs, published on March 5, 2025, emphasizes consistency in canonicalization methods, stating, “Don’t specify different URLs as canonical for the same page using different canonicalization techniques.” While this doesn’t explicitly address multiple rel=”canonical” tags, it implies that conflicting signals, such as multiple tags, can lead to errors, as search engines may struggle to determine the preferred URL.

Additionally, Surfer SEO’s complete guide to canonical tags, published on April 23, 2025, notes, “It’s important to add only one canonical tag per page. Multiple canonical tags can cause confusion for search engine crawlers, potentially leading to incorrect indexing of content.” This confusion can arise because search engines prioritize the first tag, and if subsequent tags conflict, the intended canonicalization may be lost.

Comparative Analysis: Multiple Canonical Tags vs. Single Canonical Tag
To illustrate the differences, consider the following table comparing the implications of multiple vs. single canonical tags:

This table underscores the importance of maintaining a single canonical tag to avoid SEO pitfalls.

Controversies and Uncertainties

While the evidence leans toward multiple canonical tags causing SEO issues, there is some uncertainty around the severity. For instance, Sitebulb classifies this as a low-significance issue, suggesting it may not immediately affect rankings but could cause future problems. Additionally, Google’s treatment of these tags as suggestions, not directives, means they may sometimes ignore tags altogether if other signals (e.g., HTTPS vs. HTTP, sitemap inclusion) suggest a different canonical, as noted in Botify’s insight on canonical tags, published on May 11, 2020.

This complexity highlights the need for regular audits and alignment with best practices to minimize risks.

In summary, research suggests that multiple canonical tags on a page can cause SEO issues by confusing search engines, potentially leading to incorrect indexing, diluted ranking signals, and crawl errors. The evidence leans toward ensuring only one canonical tag per page, pointing to the preferred URL, as a best practice to maintain visibility and consolidate authority. By using tools like Google Search Console and addressing technical errors, website owners can mitigate these risks and optimize their SEO strategy.