The first store targeted was Aldridge Wines in Leighswood Road at around 4.30pm on May 15. Officers say a man threatened a staff member at the off-licence with a knife and demanded money before making off with cash from the till.
The second incident occurred less than two weeks later at around 6.30pm on May 26 at a Shell garage on Northfield.
The man entered the petrol station and threatened a member of staff with a knife before stealing cigarettes.
People with information have been urged to contact West Midlands Police by called 101 or via Live Chat on its website, quoting crimes 20/434677/23 and 20/468485/23.
Those who wish to remain anonymous can call Crimestoppers on 0800 555 111