In Scrum, there is only one product and one Product Backlog for a given product. The Product Backlog is the single source of truth for the Scrum Team and the stakeholders. It contains all the requirements, features, functions, enhancements, fixes, and anything else that can deliver value to the customers and users of the product. The Product Backlog is ordered by the Product Owner based on the product vision, goals, and value.
Having multiple Product Backlogs for one product would create confusion, duplication, inconsistency, and waste. It would also make it harder to align the Scrum Teams and the stakeholders on the same product direction and priorities. Therefore, a Product Owner with multiple teams working on one product should not maintain separate Product Backlogs for each team.
The Product Owner is accountable for maximizing the value of the product resulting from the work of the Scrum Team. The Product Owner is responsible for managing and refining the Product Backlog, collaborating with the stakeholders and the Developers, and ordering the items in a way that best achieves goals and missions. The Product Owner represents the interests of everyone with a stake in the product and ensures that the Scrum Team works on the right things at the right time.
In some cases, when there are multiple Scrum Teams working on one product, it may be necessary to have some form of scaling or coordination mechanism to ensure alignment and collaboration among the teams. However, this does not mean that there should be multiple Product Owners or Product Backlogs. Instead, there should be ways to facilitate communication, feedback, integration, and transparency among the teams and with the Product Owner. For example, some frameworks or practices that can help with scaling Scrum are Nexus, LeSS, SAFe, or Scrum of Scrums.
