A lorry driver had "simply not seen" cars stopped on a smart motorway, court hears as he admits charges.
Jason Mercer, 44, and Alexandru Murgeanu, 22, died when a lorry ploughed into their stationary vehicles on the M1 near Sheffield on June 7 last year.
Figures in March showed 38 drivers were killed on smart motorways over the past five years. Most were hit by other vehicles after being unable to make it to a refuge area.
Prezemyslaw Zbigniew Szuba, 40, admitted two counts of causing death by driving without due care and attention when he appeared at Sheffield Magistrates' Court.
He will be sentenced next month.
The men were the third and fourth people to die on the stretch of smart motorway in 10 months.
Susan Fisher, prosecuting, told the court how Mr Mercer, from Rotherham, and Mr Murgeanu, from Mansfield, had been involved in a "minor bump" on the northbound carriageway of the motorway, between junctions 34 and 35, and had stopped in the slow lane.
She said Szuba's Mercedes HGV "ploughed into both vehicles".
Ms Fisher said the lorry was not speeding and there was no suggestion that the defendant had been drinking or was on drugs.
She said: "From the Crown's perspective, the defendant has simply not seen the vehicles that have stopped and not slowed down sufficiently."
Nicola Hale, defending, said her client had only just joined the motorway at junction 34 and "it was only for a matter of seconds that the (stationary) vehicles were visible".
She said the evidence in the case showed Szuba was driving "normally" and well within the speed limit just before the crash.
Deputy District Judge Michelle Jeffreys ruled that, as the likely outcome would be more than six months in prison, the sentencing had to be by a crown court judge.
Bearded Szuba, 40, of Adelaide Street, Hull, sat in the dock wearing a blue suit, pink shirt and a grey-and-black tie.
He spoke only to confirm his name, date of birth and address as well as to enter his guilty pleas.
Since her husband's death, Mr Mercer's wife Claire has mounted a prominent campaign against smart motorways and the case has become a leading example in the ongoing debate over the safety of these roads in the UK.
The stretch of road where Mr Mercer and Mr Murgeanu died is classed as an "all lanes running" (ALR) motorway, meaning there is no hard shoulder in operation.
Earlier this year, Mrs Mercer told the Telegraph that travelling on an ALR was like “playing Russian roulette with your life”.
Mr Murgeanu’s sister, Andreea, last year said that she was “really afraid that unless safety issues regarding smart motorways are reviewed more families may lose loved ones”.
In April, Grant Shapps, the Transport Secretary, unveiled an 18-point scheme to help improve the network, including refuge areas every two-thirds of a mile instead of every mile and a half.
It came after it was found that the chances of a stationary vehicle being hit by a moving one was higher when the hard shoulder is scrapped.
But ministers insisted that "in most ways" smart motorways were as safe or safer than conventional ones and in August it was revealed that seven more smart motorways are planned in England.
Parts of the M6, M25 and M3 will have hard shoulders transformed into an extra lane as long as safety improvements are implemented, Grant Shapps said.
Szuba was given unconditional bail and told he will be sentenced at Sheffield Crown Court on October 19.