Google try to not show multiple instances of the the same offer (that is, the same product offered by the merchant). We will not show the same product twice if it is uploaded by multiple CSSs. If Google is unable to detect two identical offers, they might both appear in the same Shopping Unit. In such cases, the CPCs paid to winning CSSs don’t increase because merchants are never second-priced (see next question).

Different products can appear through multiple CSSs within the same unit. If a user searches running shoes online, the ad for one model of running shoes may be from CSS A, while the ad for another model from CSS B might appear. In such cases, the CPCs paid to winning CSSs do not rise because merchants are never second-priced (see next question).