Maybe you Gertrude/Elizabeth was trying to tell you something with her last name 'Madam' maybe that was her 'activity' in life, and the baby could have been any ones.
I would also try under the name 'Unknown' there could be a man who died in the Corowa area, but the police didn't know his name so was registered "Unknown male" on the records, in fact there are 100's of people in the unknown area of the Deaths in any state records