Not always. See DBAF (both deviations from DBGT). Yes, later the former authors worked for Sueisha/Toei, as the had lots of experience copying Toriyama's style,

Not always. See DBAF (both deviations from DBGT). Yes, later the former authors worked for Sueisha/Toei, as the had lots of experience copying Toriyama's style, but back in the day they were totally legal sales of these mangas.