Do you mean that you have this death certificate -
TITLEY William Male PERTH 1031 1933
which has enough information for you to identify him to be this William BELL -
BELL William m. RILEY Louisa FREMANTLE 75 1891
"... Various Bell family documents state he was born in Ballarat around 1860, father George, mother Elizabeth."
What documents are these, can you give details. After his marriage, 1891, what documents do you have that record names of William BELL's parents - George and Elizabeth?
"...After he died, the family discovered paperwork that showed his name to be William TITLEY, and that he had abandoned a wife & children in Victoria before coming to WA..."
What paperwork is this, can you give details.