AND NOW, Despot] - our weekly glimpse into the lives of some of the world's most unusual leaders. This week the spotlight turns restlessly to Zaire and its light-fingered dictator, Mobutu Sese Seko. Being twice the man that most of us are, Mr Mobutu naturally should have twice the woman by his side. And so he does: actually, she's two women, lovely identical twins Bobi and - well, no one seems to know what the other one's name is, not even Marie Claire, which ran a feature on the sisters in this month's issue. That aside, the sight of the pair of them, one Mobutu's wife and one his mistress, makes the heart sink a little. Ravaged Third World countries can perhaps afford one Imelda Marcos-type figure. But two, both demanding pearl- encrusted gowns and foie gras and ghastly oil paintings of themselves . . . The propects for Zaire look darker than ever.