The two blasts were reportedly heard in Handsworth, Manor and the city centre in the early hours, with people taking to social media to report the noises - which some said were too loud to be fireworks.
Facebook user Cheryl Hague said: "A lot of people are talking about hearing two loud bangs in Sheffield during the early hours of today.
"Social media reports suggest they were heard in Handsworth, Manor and city - far too loud to be fireworks."
It comes a few months after a mystery early morning blast which was heard by people across South Yorkshire and up to 30 miles away.
The "massive bang" in April was supposedly heard in the Rotherham and Meadowhall area - but there were no reports of fires or explosions in the area.
After we reported on the blast, others came forward to say they also heard the noise - with one saying it was reportedly heard in Saddleworth between Sheffield and Manchester, more than 30 miles away.
It is not the first time South Yorkshire residents have been left puzzled by mysterious explosions.
Last October, residents in Long Sandall, Doncaster were left baffled by a massive late night noise with no obvious signs of what had caused the explosion or evidence of damage.
Andrew Hill said: “I felt the whole house shake and windows were rattling. “I went outside and could see smoke near the rail crossing but there were no obvious signs of what had happened.
And in November 2014, several loud 'mystery bangs' that shook windows baffled people across the country. Dozens of Twitter users from London to Glasgow claimed to have heard the strange noises, which sounded like fireworks or loud aircraft.