I'm really concerned if that really says what he meant.
The 1964 Certificate is only a Certificate of certain facts in the original record. It isn't a complete copy of the record; it isn't event a certification of all the facts.
Further, certificates in 1961 would be different from certificates in 1964 by definition. In 1961, the issuing agency was a division of Coast Province of Zanzibar; in 1964, the certificate was issued by the Republic of Kenya. See for explanation BP2's excellent work above.
The quality of Joe's legal help is not very high. He really needs someone who is paying attention to these kinds of details.
Do you have a ping list? Please add me. Thanks.
Should he not have “several samples of Kenyan birth certificates in use around” Feb, 1964 ???