Peter Ball resigned as Bishop of Gloucester after being cautioned for gross indecency in 1993.
In 2015 he was convicted of a string of sex offences and jailed for 32 months.
He was found guilty of committed abuses whilst serving as Bishop of Lewes between 1977 and 1992.
The Church of England has admitted that Peter replaced his identical twin brother, the former Bishop of Truro Michael Ball, in the 1990s on a number of occasions.
The Diocese of Truro is now investigating its records and has appealed to churchgoers who could have been present at services or events when one bishop acted as the other.
Speaking to BBC Radio Cornwall the current Bishop of Truro, Rt Revd Tim Thornton, said it was not clear if Peter Ball had moved to Cornwall to live with his twin after his resignation.
He said: "We have one or two bits of evidence now where it does appear as if Bishop Peter went and did things which Bishop Michael should have been doing.
"It might be that Bishop Peter thought that it was clear that he was being Bishop Peter, and on some occasions might have made it very clear at the beginning that he was there in place of his brother, but it might not have been evident to everybody."
The Church has also said that finding the correct information has not been straightforward because nobody was working in the diocese at the time, and paper and electronic records have not been easy to get hold of.
Early investigations claim that despite his criminal caution Peter Ball was given a "restricted permission to officiate" in the Diocese of Truro.
The information will now be given to the Goddard Inquiry, which is investigating how the Church of England - among other institutions - handled allegations of sexual abuse cases, and whether any were covered up.
