This is not quite correct: translations do not have unique locale codes, and it's OK for a bunch of translations to translate the same locale.

The use case here is if you develop a third-party application like "SuperCountdown", you might want to translate it into BritishEnglish. You can add a translation file to your application and distribute it with the rest of your code, with just your application's strings, and it will supplement the existing main translation file.

This should be OK without the setUniqueMethod() call.