George Thomas Turner and Mason Pearson, both 17, died after the Volkswagen Bora car they were travelling in crashed with a Ford Focus on the A61 between Busby Stoop and Carlton Miniott in North Yorkshire on March 7, last year.
Another two passengers in the Bora, an 18-year-old man and a 17-year-old boy, were taken to hospital in a critical condition and later discharged.
The driver and passengers of the Ford Focus, a 27-year-old man and a 24-year-old woman from outside the area were discharged from hospital following treatment. Their three-year-old daughter and a six-month old son were kept in hospital for observation before being discharged.
The driver of the Bora, 24 year-old Luke Ridley from Thirsk, pleaded not guilty at an earlier court hearing to two counts of causing death by dangerous driving and five counts of causing serious injury by dangerous driving.
William James Corser, 18, of Thirsk, the teenage driver of a third vehicle that was not involved in the collision, but driving in company with the Bora, also pleaded not guilty to one count of dangerous driving on the same date.
Both men appeared at Teesside Crown Court today, at the start of the scheduled trial, where both changed their pleas to guilty on all counts.
Both were granted conditional bail with an interim driving disqualification.
They will be sentenced at Teeside Crown Court on Friday, July 30.