Teenagers at hundreds of secondary schools are being entered for two English qualifications to boost results.
As well as taking GCSE English, these pupils are also taking an International GCSE (IGCSE) in the subject as schools attempt to achieve better grades and secure a higher ranking in league tables, the Times Educational Supplement (TES) reported on Friday.
Around 320 secondaries are believed to be entering at least some of their students for both courses, a strategy which is being promoted by the Performance in Excellence Club (PiXL).
The not-for-profit club, run by former headteacher Sir John Rowling, offers schools a number of ways to help improve GCSE results.
An estimated 400 secondaries across England are part of the club and, of these, about 80% are thought to have at least some pupils taking GCSE and IGCSE English, the TES reported.
Sir John said the main purpose of the plan is to help more students achieve a decent English grade, but he acknowledged it was also a "belt and braces" approach for schools.
"Most heads thought the IGCSE was just for independent schools and that it didn't count towards league tables, but we have studied it very carefully and we've found it can be very appropriate for some state school students," he told the TES.
The Government announced two years ago that state schools in England would be able to offer IGCSEs, and that the qualifications would count towards league tables.
The exams have long been favoured by many private schools, which argue that they are tougher than GCSEs.
They are considered more traditional, with pupils taking exams at the end of the two-year course rather than in bitesize chunks.
Sir John told the TES that more schools have become interested in the strategy following this summer's GCSE English controversy.
Headteachers say thousands of teenagers received lower than expected grades in the subject this year after the grade boundaries were moved between January and June.
Sir John told the TES: "Teachers work like slaves all year then, at the end of it, get messed about.
"They invest all that effort just to be scuppered at the last minute, so I say if there is another alternative then use it."
He also told the Press Association: "Schools are unwilling to risk their futures and their kids' futures on something that appears not to be altogether rational."
Sir John added that the main, moral reason for entering pupils for two exams was to improve pupils' grades.
The two qualifications are not the same, he said, and focus on different areas of English.
But he said there was also a "pragmatic" view.
"You can't get away from the fact of offering belt and braces as well."
Figures published in August showed that 400 state schools are now teaching IGCSEs compared with 97 in 2010 and 220 last year.
So-called IGCSEs in subjects such as English, history and biology are proving particularly popular with schools, according to data published by University of Cambridge International Examinations (CIE), which offers the qualifications.
A Department for Education spokeswoman said: "This is clearly not in the best interests of pupils. Schools must only enter students for the qualifications that are right for them, not for the cynical reasons this suggests.
"It is essential that the secondary school accountability system minimises perverse incentives and acts in the interests of all pupils. We have already announced our intention to launch a consultation into this system and will do shortly."
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