custom_json are non-consensus operations. This means that the blockchain will never reject any (except if authorities are missing).

Therefore, HiveSQL (like the blockchain) includes all broadcasted custom_json, even if "duplicate" or considered as invalid by a 2nd layer app.

This is why there is no hive-engine "state" table in HiveSQL because the hive-engine code is closed source and HiveSQL doesn't know how to interpret those operations.