Complex sentence: Dimension Zero started out as a demo group in 1992 but only officially self promoted as a band 2000, often mistaken for the Swedish band of the same name (formed in 1996).
Split into simpler sentences: Dimension Zero started out as a demo group in 1992 but was officially promoted as a band in 2000. It is often mistaken for the Swedish band of the same name (formed in 1996).