According to this information from Mayanka, sub-genres and duplicates of a genre don't get pulled in when a genre is marked as a duplicate. At the moment we seem to be prohibited from marking a genre as a duplicate if something else is already a duplicate of it, but there's no prohibition on marking a genre as a duplicate if it has sub-genres.
So, the duplicate genre process should go like this: 1. Find a genre A which you think should be a duplicate of a different genre B. 2. Check A for sub-genres. If it has any, edit each one to be a sub-genre of B. 3. Then mark A as a duplicate of B.
So, the duplicate genre process should go like this:
1. Find a genre A which you think should be a duplicate of a different genre B.
2. Check A for sub-genres. If it has any, edit each one to be a sub-genre of B.
3. Then mark A as a duplicate of B.