This question resolves as YES iff any two African countries announce their dissolution as sovereign states and replacement by a single sovereign state. The Senegambian Confederation of the 1980s is partially an example, since both states retained their separate UN membership (but then again, Belarus and Ukraine were separate UN member states from the Soviet Union, so that doesn't really count for much). Another example involving an African country was the United Arab Republic of the late 1950s, when Egypt merged with Syria.

Mergers involving both African and non-African countries count if at least 4/5 of the population is in Africa.