The registration book referred to in the Kenyan COLB may actually say Zanziber.
Mombasa came under the control of the sultan of Zanzibar in 1840 and was leased to the British in 1895. From 1905 to 1907 it was the capital of the British East Africa Protectorate. In 1920 it became capital of the British Protectorate of Kenya.
Based on your comment, I think that until this is resolved, we should refer to Omarxist as ‘President Zanzibar.’