Many surnames have spelling variations. Tracking back through historical records will often provide evidence of a names evolution. Names were frequently changed with arrival in Australia to make them easier to spell or pronounce. Many Prussian names were anglicized.
Typically the name adopted in my database is that recorded in the birth or christening record. However, exceptions to this rule have been made when it is clear that errors have been made and, in few cases cases, simply so as to keep families together in the index. In these cases, the name from the birth/christening record will sometimes be shown in the ‘Birth Memo’ field.