Hi ricg thanks for the great question! We have a docs page that speaks to this https://docs.powersync.com/usage/sync-rules/client-id:

"PowerSync does not perform any validation that IDs are unique. Duplicate IDs on a client could occur in any of these scenarios:

- A non-unique column is used for the ID.

- Multiple table partitions are used, with the same ID present in different partitions.

- Multiple data queries returning the same record. This is typically not an issue if the queries return the same values (same transformations used in each query)."