Robbers struck twice at convenience stores in Trafford in the space of just a few minutes.
The first robbery took place at about 9.20pm on 16 December 2012 at the McColls store on Framingham Road, Brooklands.
Minutes later, thieves struck at the Eastway Stores on Eastway, Sale. Police believe the two incidents are linked.
During the first robbery, two men wearing balaclavas pulled up in a black Mazda 6. They went into the store and one of the men was carrying an axe. The thief climbed over the counter and used the weapon to try and force open the till.
After failing to prise it open, they stuffed some cigarettes into a bedsheet and left in the Mazda towards Marsland Road, Sale.
Minutes later, thieves struck at the Eastway Stores on Eastway, Sale. Again, two masked thieves went into the store carrying an axe.
One of the shopworkers was injured after being struck with the weapon and needed treatment at the scene for a cut to his elbow. While this thief was attacking the shopworker, the other stole the till from the counter.
The black Mazda was later found abandoned on Haydock Avenue in Sale.
Police are now appealing to anyone with information to come forward.
Detective Constable Chris Aunins said: "The offenders were are looking for are dangerous men with access to weaponry and with a propensity to use violence to get their hands on cash. Luckily the shopworker was not seriously injured but the fact he was attacked with an axe means his injuries could have been far worse.
"We need to find the offenders, so I would appeal to anyone who has information about either robbery to call us.
"In particular, I want to hear from anyone who has information about the whereabouts of the Mazda at about the time of either robbery to come forward."
Anyone with information is asked to call police on 0161 856 9168 or the independent charity Crimestoppers, anonymously, on 0800 555 111.