Barry earned his second in the 86th minute when his feeble strike found the back of the net to make it 3-0 for his side.
Guinea looked a stronger side especially in the opening moments of the game and the result was an opener that came from a weak back pass by the Namibians.
Moussa Camara ensured the Southern Africans would not get an equaliser in the middle of the first half when he reacted quickly and stopped Elmo Kambindu’s effort with a timely dive. Camara was called to action again when he tipped over the bar a 30-yard free-kick from Ambrosius Amseb.