On a product page I have two aggregated ratings for one product at different places, which means they contain identical information. I want to have them twice on that page due to ux reasons, but I'm not sure if I can markup them with schema.org everytime or if this would be a useless duplication.
Wondered if there is a solution with
itemref but in my opinion it's not helpful for this task.
Unless you use
itemid, consumers can’t be sure that two (or more) items are (about) the same thing. So they would learn that your
Product item has two
AggregateRating items. Consumers might try to deduce that both items should be the same (e.g., by comparing
url values), but you would better not rely on this.
So you should use the
itemid attribute (Schema.org does not yet claim to support it, which Microdata requires, but according to this issue, it’s intended to document it sometime), giving both of your
AggregateRating items the same URI.
But consumers don’t necessarily support
itemid, so they might still have problems guessing that these items are about the same thing.
So ideally: markup only one occurence (per document) with Schema.org.