The first occurred at around 8.11pm on Saturday, February 12 in Westbourne Street, when the suspect entered a store holding a large knife and demanded money.
He stole a significant number of cigarettes, cash from the till and left along Coleridge Street in the direction of Sackville Road.
The next day, a man entered a convenience store in Goldstone Road at 7.05pm carrying a large knife.
He left without taking anything after being confronted by the owner, making off northbound along Goldstone Street and left into Shirley Street.
On both occasions, the suspect was described as a white man in a dark hooded top, with his hood up and a face mask on.
Anybody who can help identify the person in this photograph, or has any information which could help the investigation, is asked to contact police online or by calling 101, quoting serial 1147 of 12/02