Google’s John Mueller advises against copying the same structured data onto multiple pages of a website.
If a page needs to contain structured data, it should be unique to that specific page.
This advice was given during a Google Webmaster Central office-hours hangout where Mueller addressed the following question:
“Can a service review be used on only one page, or can it be shared on multiple pages related to the same branch? We have reviews for particular branches marked up, but we also have general sub-pages that we mark up too.”
Since service reviews are marked up using structured data, Mueller offered general guidance for all structured data:
“In general, structured data on a website or a page should be specific to that particular page. It shouldn’t be something where you say, ‘This is a review for our business in general, and therefore we’ll put it on all the pages of our website.’
It should be very specific to the primary topic of that page. From that point of view, I generally avoid mixing and matching reviews or trying to create a set of aggregated reviews based on what you’d like to show on a website. They shouldn’t be testimonials; they should actually be reviews.”
Mueller did not elaborate on the consequences of duplicate structured data on a site, but it can likely be assumed it will be treated similarly to any other duplicate content.
In any case, when it comes to the body content of a page, it’s usually best to avoid duplicating anything, regardless of whether it’s marked up with structured data.
