The 27-year-olds have been charged over the alleged sexual assault of a 17-year-old at a unit in Parramatta in western Sydney in December 2015.
The men cannot be legally named as they were 16 at the time of the alleged offences.
"It's very disturbing behaviour," the police prosecutor said while declining to outline accusations during a bail hearing at Parramatta Local Court on Thursday.
The twins were arrested at their parents' western Sydney home on Monday.
Defence solicitor Lionel Rattenbury said his clients strongly denied the allegations and would defend the matter.
The court heard witnesses would say the teenage girl was drugged and unconscious during the alleged assault.
They were granted bail after Judge Cate Follent found strict conditions could be imposed to mitigate risks.
This was despite the case against the two men being strong and supported by two independent witnesses, she said.
Their mother and three sisters watched on from the public gallery.
They were handed tissues by court officers as one of the men appeared on-screen from prison and gasped in relief as bail was granted.
Outside the courtroom, their mother collapsed to the ground.Â
Sheriffs were called, water was fetched and Mr Rattenbury placed his jacket under her head.
Prosecutors opposed bail, saying there was an unacceptable risk the brothers would fail to appear in court, endanger the alleged victim and interfere with prosecution witnesses.
While the alleged victim approached police in 2015, she was too traumatised to make an official statement, the court heard.
After a forensic review of the alleged crime, police re-approached the complainant years later and obtained the statement.
Mr Rattenbury disputed that his clients posed an unacceptable risk, saying the pair had no criminal record and had no criminal associations.
"The thought that now suddenly these people pose a risk to the community ... is not right," he told the judge.
The two 27-year-olds did not know where the alleged victim lived and did not know the identity of the civilian witnesses, he argued.
The pair lived with their parents and had strong community ties being raised in the church, Mr Rattenbury said.
One worked as a security guard while the other had just sold his barbers businesses, he told the court.
A surety of $5000 for each of the brothers was put up by family which will be forfeited if they do not attend court.
Their matters will return to court on July 16.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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