The boys were aged 4 and 10. The driver of the car, believed to be the boy's mother, and another female passenger, remain in a stable condition in hospital.
The crash occurred on the northbound carriageway near junction 15 at around 11.25am this morning.
The motorway has now reopened.
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Albert Starkie, 80, was found dead in his cell at Strangeways on Tuesday. His daughter Karen, 57, kept the abuse a secret for 45 years.
In a Facebook post, Ian Hanson said a statement released by Mr Danczuk on Thursday was "totally lacking in detail or substance".
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