The attacks were in the 3800-block of West Myrick Street, on Feb. 26 at about 9 p.m. and in the 7800-block of South Pulaski Road Tuesday at about 10:30 p.m.
Police say victims were walking by themselves when they were approached on the street and robbed.
Police are looking for two or three suspects. One offender fled in a green mini-van.