Emmanuel Adanemhen, 50, and Eduwu Obasuyi, 40, pleaded guilty at Maidstone Crown Court to their part in sophisticated fraud and money laundering scams.
A Kent Police spokesman said that Adanemhen arrived in the UK as an asylum seeker in 1998 and had assumed the identity of a deceased Portuguese man by changing his name by deed poll and on driving licences.
He used the fake identity to open bank accounts to launder funds from the fraud schemes which included dating website scams, false inheritance scams, overseas lottery wins and shipping frauds.
Police were led to Adanemhen after they arrested Obasuyi, of Friern Road, East Dulwich, London, who was detained as he was about to board a plane from London to Lagos, Nigeria.
Detectives found that the two defendants had moved more than £4 million through their various accounts which had come from victims in countries including Germany, Norway, Switzerland, New Zealand, Canada, United Arab Emirates and across the USA.
One elderly victim from Florida was conned out of 2.9 million US dollars with the total lost by victims is estimated by police to be in excess of £25 million.