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.
- Also look at: Why does the amount of indexed pages fluctuate so much?
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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:
In the Visibility Index history above, which comes from the domain hertz.de, 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 hertz.de and hertz.ch clashed in the German search market (google.de) which proved to be a Duplicate Content problem for Google.
You can clearly see that a fall of the visibility of hertz.de on the German search market (google.de) always brought along a rise in the visibility of hertz.ch and the other way around.
This becomes even clearer if you zoom in to the specific time frame:
Google apparently had difficulties assigning each domain to its rightful country and rotated between the content on hertz.de and hertz.ch in the rankings for the German search market (google.de).
This had far-reaching consequences for the ranking of hertz.de in the German search market, as you can see in this ranking development:
Based on the above ranking development, you can clearly see that Google happily interchanged content from hertz.de with that of hertz.ch. 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 hertz.de, 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 hertz.ch in Germany should be much lower than for hertz.de.– Hanns Kronenberg, SISTRIX