Did my great-grandfather Patrick Francis Maher use his brother John's name to travel to Australia?

My great-grandfather Patrick Francis Maher was born on 8th September 1852 in Thurles, Tipperary.  Parish registers show his baptism taking place in Thurles in the diocese of Cashel and Emly.   His parents were James Maher (born 1812) and Hannah Myers (born 1811), who married in 1834.   According to a story he was said to have written about his trip to Australia he came out on the "Jerusalem" in 1875. He told my grandmother that he was sorry he had stolen money from his parents for the trip.  The passenger list for the "Jerusalem" lists John Maher and Dennis Maher but no Patrick Maher.  Patrick had brothers named John (born c.1846) and Dennis (born c.1850) and there are records of Dennis living in Australia, but no record of John being here.  Two of his other brothers, Richard and William, also came to Australia.  I would like to find proof that John remained in Ireland so it can be proven Patrick used his name for some reason.