See the bellow points in order to fix the issue.

1. Log through SLF4J only.
2. Check for multiple appenders targeting the same output.
3. Ensure only one logging implementation is present on the classpath.
4. Set additivity="false" to avoid message propagation.
5. Avoid duplicate logging statements in your code.
6. Make sure there is a single SLF4J binding.

By following these steps, you should be able to prevent duplicate log messages in your Java application.