Even for Utilitarians, this duality serves as a line in the sand. Some considerations will clearly fall on one side or the other: assuring humans are not tortured is an obvious negative morality concern, while assuring humans have access to affordable sushi is probably a positive morality concern.
For pure “util-driven” Utilitarians, it’s possible to claim there are no metaphysical rights, only degrees of better or worse (which I am actually pretty convinced is a true idea), thus making this distinction meaningless. But they must still respond to a question of cost, and this duality really only emphasizes that all moral considerations can fall into two buckets based on higher cost (negative morality) or lower cost (positive morality).