If a config option is specified multiple times in a configuration file, no error or warning is given. The value will be silently overridden, with the most recently defined value being used. See linked test results for more details.
Steps to replicate: Duplicate any config option. The node will start up with no errors or warnings. Even if the value is the same, an error or warning should be produced so that the node operator can confirm that A) the intended value is specified, and B) if a change is made in future, the change produces the expected result (not necessarily the case with duplicated config options).