The Product Backlog is the collection of all the user stories that are part of the project, whilst the Sprint Backlog is a subgroup of that, a smaller collection of user stories specific to a particular Sprint. Basically all of the user stories you will deliver in that Sprint.
So there’s only one Product Backlog, but each Sprint will have its own Sprint Backlog hence, you will always have multiple Sprint Backlogs, one for each Sprint.
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