Report duplicate IDs
Events with duplicate IDs cannot be saved into db. It's deliberate, as ID is also used as primary key. However, duplicate IDs should be inspected and originators notified - either their IDs do not have sufficient entropy, or their connectors generate duplicate messages for whatever reason.
Bonus: originator can be notified automatically if duplicate ID comes from the same connector.
We should either watch logs or propagate error into runlog and report from there.