Is it possible to identify Duplicate Content through the Visibility Index history?

Yes, a potential Duplicate Content problem can have a visible impact on the SISTRIX Visibility Index, as it can lead to a negative impact for a large part of the domain’s rankings.

It is quite possible that the SISTRIX Visbilityindex will show the same ups and downs which can be seen within the number of indexed pages in case of a duplicate content problem.

Example of an external duplicate content problem visible within the Visibility Index

If a Duplicate Content problem exists for a longer period of time and will therefore have a negative impact on the rankings of the affected website, it will look something like this in the SISTRIX Visibility Index:

Visiblityindex history for the domain with a visible Duplicate Content problem

In the Visibility Index history above, which comes from the domain, we see a noticeable up and down within the red box, which cannot be explained through a Google algorithm change. Upon further investigation it became apparent that this pattern was also neither caused by a (failed) website relaunch or a Google-Penalty.

Such a typical zig-zag-pattern in the SISTRIX Visibility Index is much more likely to point to a cross-domain Duplicate Content problem, which is also called external Duplicate Content.

In the case of the car rental company Hertz, the country specific websites and clashed in the German search market ( which proved to be a Duplicate Content problem for Google.

Visibility Index comparison of both Hertz country-domains in the German search market

You can clearly see that a fall of the visibility of on the German search market ( always brought along a rise in the visibility of and the other way around.

This becomes even clearer if you zoom in to the specific time frame:

Zoom of the Visibility Index comparison for both domains in the German search market

Google apparently had difficulties assigning each domain to its rightful country and rotated between the content on and in the rankings for the German search market (

This had far-reaching consequences for the ranking of in the German search market, as you can see in this ranking development:

Ranking development of both hertz domains during the time of the Duplicate Content problem

Based on the above ranking development, you can clearly see that Google happily interchanged content from with that of This game continued on for a while until Hertz finally solved the problem themselves.

Hanns Kronenberg ran a fine analysis on the Duplicate Content problem of Hertz and showed why this is problematic.

There are two reasons why this is problematic for Hertz. In the weeks with low visibility for, the sum of the index values for both domains is much lower. This means that in these weeks results for Hertz were found at a much rarer rate in the search results. Secondly, the click through rate (CTR) for search results of in Germany should be much lower than for– Hanns Kronenberg, SISTRIX

– Hanns Kronenberg, SISTRIX

Video Explanation by Matt Cutts / Google

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