Ex-Staff Sgt Alan Dobison, 65, appeared in the Gazette in November wearing two GSMs at the Remembrance Day parade in Seahouses.
The picture has caused a stir because a person is only allowed to wear one.
But Mr Dobison, of Seahouses, said he was incorrectly sent the second medal when he applied for a replacement in 1994.
He said: "I am an expert soldier, not a medal expert.
"I have worn them in massive parades and ceremonial events and nothing has been said until now."
Mr Dobison had a GSM with the Aden clasp but those recognising his work in Borneo and Northern Ireland had been lost.
He wrote to the Ministry of Defence and was sent another GSM with the clasp and his Mentioned in Dispatches award.
Mr Dobison said: "In 1994, thousands of people applied for medals because the following year was the 50th anniversary and there was huge parades all over the country.
"It was an administrative error on their part that I was sent another medal and ignorance on my part."
He added: "I am annoyed that someone went behind my back and didn't have the gumption to ask me about it face to face.
"It was an innocent mistake that could have cleared up in a second."
The Gazette had received a letter and an e-mail about the medals and many messages have been left on an army rumours internet site, where there is a link to our site, www.northumberlandtoday.co.uk
The Special Air Service Regimental Association has written to Mr Dobison, after being told about it by a member of the public, and acknowledges it was a mistake.
A letter said: "I hope this matter is now closed."
Mr Dobison served in the SAS from 1963 to 1975 and then joined the American Army. He was part of a team which went to Vietnam to trace those who were missing in action.
He was captured and his knee smashed. He was awarded the American Purple Heart.