Richard and Jane Charlotte Banks also had a daughter Jane in Newtown Geelong in 1859 rego 2911.
I would think that as her name on the birth registrations is Wilson that this is her maiden name and she married as a widow under the Carrighan name.
It is interesting that a Terentius Julius Carringhan aged 6 died in 1854 parents Terentius and Charlotte Jane Powell. He was born in England. reg 2828
I think this their arrival into Australia note the TWO Charlotte Janes!!! I looks like a widow and her children.
source:
http://proarchives.imagineering.com.au/index_search.asp?searchid=23CARRIGHAN ARTHUR G 17 JUL 1853 HELEN LINDSAY B 043 002
CARRIGHAN CHARLOTTE J 20 JUL 1853 HELEN LINDSAY B 043 002
CARRIGHAN CHARLOTTE J 42 JUL 1853 HELEN LINDSAY B 043 002
CARRIGHAN JULIA 3 JUL 1853 HELEN LINDSAY B 043 002
CARRIGHAN T JULIUS 6 JUL 1853 HELEN LINDSAY B 043 002
Due to the wide range of childrens ages it is not imposssible for the older Charlotte to have been born Charlotte Wilson, married a Powell, then a Carrighan then Banks.
The older children Charlotte Jane and Arthur G. would have been born prior to civil registration.
Julia should have been born c 1850 and T. Julius c 1847 can't see anything on Free BDM except got a Julia Augusta CARRIGHAM for the June Qtr 1850. in Pancras St district. volume 1 page 320.
I think that you may just have to purchase some certificates to sort out what is happening. The two marriages may well be: the younger Charlotte Jane to Martin Marshall and the older Charlotte Jane to Richard Banks.
regards
Robyn in Australia