If your mom is Mauritian and you were born outside of Mauritius you qualify for citizenship based on descent.
http://www.gov.mu/portal/site/Assem...54555fc808010VgnVCM100000ca6a12acRCRD#citizen
In order to have dual citizenship you have to get authorisation from the SA government to retain your SA citizenship BEFORE you get citizenship of another country.
http://www.home-affairs.gov.za/Citizenship.html#C2
Thats easy then.