Brother as far as O and A levels are concerned you dont need to put a stamp on it cause if you read on the back side of the original O and A level Mark Certificates its clearly written that you are prohibited to alter or put anything on the document. And as far as IBCC equivalence is concerned it already comes with a red seal/stamp on it. And honestly i dont know if you can even verify your equivalence because it is a certificate which already after due verification is awarded to you.
As far as bachelors degrees are concerned yes you have to get it verified from the board/university or HEC. Its a must. They put a stamp of verification on the back side of your degree.
Hope all this helped you.
Regards