Or the alternative option:

That Alfred George Dixon was the change of name, and Augustus Caesar FINNY/FYNNEY his original one.
- Because here is Susan Jones again in 1871
FINNY, Augustus C Head M 52 1819 [no occ given] Staffordshire Leek
FINNY, Jane Wife F 50 1821 Lanc Manchester
JONES, Susan Visitor F 21 1850 Dressmaker Bristol

RG number:RG10 Piece:4066 Folio:45 Page:11
Address:Rochdale Road Beecroft Terrace, Blackley County:Lancashire

As both children were with foster families in the IOM when under a year old, perhaps Susan went to the IOM to give birth (because unmarried?) and Augustus/Alfred gave a false name as the father for the bapts/birth record.

Then, after his death, Susan became his "widow" under his real name, and brought her children back to England to live with her before 1891. Or she might have married him if/when Jane died?

Have you looked for Jane, and for his will?

Sue