I configured two aggregation rules ：by entity and by service，
This is because our system group needs to see host-based alerts, but the business group wants to see service-based alerts.
In the configuration preview, the rules can take effect normally. But in the episode review，the events will only be aggregated according to the service.
The document says that it is possible to aggregation multiple rules for an event ： https://docs.splunk.com/Documentation/ITSI/4.1.2/Configure/CreateAggregationPolicies When creating a new policy, be mindful of the policies that have already been created. Multiple aggregation policies can be created with filtering criteria that capture the same set or subset of events. If the same notable events are captured by more than one policy, the action rules from each policy are applied to the notable events.