You are a German and Namibian citizen?
As a dual national you have always travelled with your German and your Namibian passport?
It is now no longer necessary for dual citizens to obtain the so-called “declaratory visa”. With the letter from “Office of the Ombudsman” dated 11. March 2015 the Namibian authorities confirmed the non-requirement of the declaratory visa.
You can find the document here:
Legal opinion by the Office of the Ombudsman PDF / 313 KB
Due to positive feedback from travelers in recent months the Embassy of the Federal Republic of Germany in Windhoek will, therefore, no longer issue declaratory visas with effect to 1st January, 2018.