Hybris comes with bundled Log4J logger. This is used for every logging activity in hybris.
We can define log levels for each extension and even each package. So if we have defined logger level for sub package, then it will execute twice. For eg;
log4j.com.package.name = debug,appconsole
log4j.com.package.name.subpackage = debug,appconsole
So every logging activity for subpackage will be run twice, once for parent package and one for sub package.
We can disable it via: