Complex sentence: The NZGB encourages the use of original Māori names and has given some places official double names, either as alternative names (Mount Taranaki or Mount Egmont) or dual names (Matiu/Somes Island).
Split into simpler sentences: The NZGB encourages the use of original Māori names and has given some places official double names. These can be expressed as alternative names where officially either name could be used (Mount Taranaki or Mount Egmont) or dual names where both names should be used together (Matiu/Somes Island).