By leveraging the notifyNewTables and notifyTablesClose methods of the Metadata you can maintain an updated map of users and their respective active subscriptions.
By adding the list of requested groups for the involved user in the notifyNewTables method and subtracting the groups from the same user as the notifyTablesClose is called, you can use this map to make decisions in the notifyNewTables method to reject any duplicates (by throwing a CreditsException).

- https://sdk.lightstreamer.com/ls-ada...bleInfo%5B%5D)
- https://sdk.lightstreamer.com/ls-ada...bleInfo%5B%5D)

Regards,
Giuseppe