Multi entry visa is the £10 UK entry tourist visa isn't it?
The single entry (rip off visa) is the one purchase via the Embassy in London prior to entry, a friend purchased one for the year thinking they got a bargain,a few months later they had to return to the UK for personal reasons, on their return to Turkey they were asked for £10 for the tourist visa as the one purchased in the UK was no longer valid as they had left Turkey.