I suspect they lied to the registrar who would have had no way of checking as there were no birth certificates issued in IoM at that time (the copies of parish registers were not called until c.1911 - about the time old age pensions were being introduced in UK and thus there was a finacial advantage to be gained by subterfuge) - the age difference would have raised some comments and the 27 (I think their average age!) was probably just about 'get awayable' with.