Could well be.
Looking at Matilda, the possible sister of Robert, she might be this Matilda:
https://www.ancestry.co.uk/imageview...rn&pId=6893423
She is living in Barnstaple, the daughter of John Norman, a carpenter. John, good man, givs and entirely different pob on every census: Devon, Newport Hants and Barnstaple.
There is a large gap between Matilda and her sister Emma, and this marriage of a John Norman in Barnstaple:
https://www.findmypast.co.uk/transcr...F514235772%2F1
Sadly, it is only a transcript of John's marriage to Elizabeth Gibbons 8 December 1821, and even if he were a widow, it would prove nothing, but I cannot see what might have happened to Matilda.