Verdict
Yes — you can hold Poland and South Africa citizenship simultaneously.
Poland
Dual citizenship policy
Permitted — Poland allows dual citizenship (though it does not formally recognize it; Polish citizens are treated as Polish while in Poland).
South Africa
Dual citizenship policy
Permitted — South Africa allows dual citizenship (must apply for retention before acquiring another nationality).
Both Poland and South Africa permit dual citizenship. You can acquire, hold, and use both passports simultaneously without legal restrictions.
This assessment is based on each country's current nationality law. Dual citizenship rules can change — always verify with the relevant consulate or an immigration attorney before making decisions about renunciation or acquisition.