Current exam plans involve Diplomas, Apprenticeships, GCSEs and A-levels
MPs have called on the government to make clear its intentions on the future of Diplomas, GCSEs and A-levels.
The schools select committee says it suspects "the wheel may have turned full circle" and ministers intend to have one over-arching qualification.
This was proposed in the Tomlinson report on 14-19 learning in 2004, but scotched under Tony Blair's leadership.
But the government has said it wants "the best of existing qualifications within the Diploma framework".
Diplomas are employer-designed qualifications at foundation, intermediate and advanced level, combining theoretical and practical learning.
They include essential skills and knowledge, practical experience and "functional skills" in English, maths and information technology.
The first five subjects start being taught in England this autumn - amid widespread concern about their complexity and the readiness of schools and colleges to teach them.
Now, in a report on assessment, the MPs have said: "With a full government review of Diplomas, GCSEs, A-levels and other general qualifications announced for 2013, we are beginning to suspect that the wheel may have turned full circle and that the government intends to adopt the Tomlinson proposals after all."
They said: "The whole education sector would welcome greater clarity on the future direction of Diplomas.
"We urge the government to make clear what its intentions are for the future of Diplomas and other 14 -19 qualifications and whether it is, in fact, heading towards one, over-arching framework for all 14-19 qualifications as Mike Tomlinson's Working Group on 14-19 Reform proposed in 2004."
The committee warned that schools and colleges, which have to work together to cater for Diploma students, could not be expected to do so effectively when "the accountability regime" - with its league tables - "places them in direct competition with each other".
A spokeswoman for the Department for Children, Schools and Families said Diplomas were "a massive reform" that would offer "exciting new choices for young people to learn what they need to in the way they want to".
Everything was on track for September 2008, she said.
"Teachers are preparing well for the start of Diplomas in September, with three days of face-to-face training at the start of an on-going support package."
She added: "We have set out our plans for the future in our 14-19 qualifications strategy and have announced that in 2013 we will review, in the light of the evidence of the impact of Diplomas, the qualifications on offer to young people."
What that strategy said was that the existing system was overly complex and difficult for youngsters and their parents and advisers to understand.
Instead there would be a new three-pronged strategy of Diplomas, GCSEs and A-levels, and Apprenticeships up to the 2013 review.
Ministers have already decided ahead of the review that Applied A-levels will be scrapped.