No it isn't - you can't enter Africa twice.

"Only one intercontinental departure and one intercontinental arrival permitted in each continent.
Exceptions: Two permitted in North America. when one is a transfer without stopover.
Two permitted in Asia when one is a transfer without stopover or on direct single plane service between the Southwest Pacific
And Europe.
For travel to/from or via Ghana/Nigeria two permitted in Europe when one is a transfer without stopover between
Ghana/Nigeria and another continent."

[This message has been edited by christep (edited 01-11-2003).]