The pair, named locally as Ryan Theobald and Janis Kozlovskis, died in the early hours of Saturday morning after a night of horrific bloodshed which also left a third man in hospital with stab wounds.
A 17-year-old is in custody in connection with the attacks which took place near to the junction of Silver Street and Hall Gate.
Grieving friends have been paid tribute to the pair in a string of emotional social media posts.
One said: “RIP Ryan - It’s true, he always takes the good ones first, my thoughts also with the other lad’s family RIP boys.”
Another wrote: “Rest easy up there Ryan. Sleep tight. You was such a happy lad and always smiling. I’ll treasure the memories we have made through college forever.”
Another posted: “Sad world we live in... Rest in paradise Janis Kozlovskis and Ryan Theobald.”
“Rip Ryan Theobald, forever a great person. Great few years we laughed with you and your family ! Thinking of your family,” another posted.
Another tribute to the pair said: "You both were some boys - rest up brothers only the legends die young.”
One posted: “R.I.P Ryan Theobald didn't know him long but used to work together – was a good lad hard working it's sad how ur gone so soon fly hight bro.”
A string of town centre streets were sealed off by police for more than 18 hours as detectives pieced together the tragedy which took place shortly after 2.30am on Saturday.
Police were called at 2.39am to reports that two men and a teenager had been stabbed following an altercation outside a bar in Silver Street.
Officers attended the scene alongside the ambulance service, and one of the men and the teenager were transported to hospital via ambulance, where the teenager, aged 17 and understood to be Janis, sadly passed away. The 18-year-old remains in hospital with minor injuries. Despite the best efforts of police and paramedics, a further man, aged 21 and understood to be Ryan, was also sadly pronounced dead at the scene.
Doncaster District Commander, Temp Chief Superintendent Ian Proffitt, said: ““We know incidents like this can be really worrying for local communities, so if you have any concerns, please do go and speak to our officers - they are there to help and support you.”
Detective Chief Inspector Mark Oughton, leading the investigation, added: “We are keen to hear from anyone who was in the town centre in the early hours who might have witnessed what happened.
“If you were in the area at the time, if you saw what happened or if you think you may have mobile, CCTV or dashcam footage, please call 101 quoting incident number 135 of 29 January. Any information, however small, may assist us in bringing those responsible to justice.
“Alternatively, you can stay completely anonymous by contacting the independent charity Crimestoppers via their website Crimestoppers-uk.org or by calling their UK Contact Centre on 0800 555 111.”