[logback-user] Collisions between primary and included configuration files

Our main logback.xml file is jarred up with our application. We'd like to be able to have an "override file" in which we could simply specify the settings we wanted to be different than the main file. I thought about using the file inclusion feature to include the override file from the main config, but the manual doesn't describe the behavior when the included file and the primary file have conflicting settings (for example a logger level). Any ideas on how to accomplish this? Thanks!