I think that that was the problem - same type of aeroplane.
I could be wrong but I think that they got G-BJCB as a reg in the standard alphapetical run and then managed to keep it with the next airframe. When the CAA realised the nightmare that it could create in paperwork, having two airframes of the same type with similar frame numbers, it was decreed that each reg would only ever apply to one airframe. As a sweetener OOS registrations were then allowed.
I suppose it begs the question as to how they manage in USA, Germany etc???
I remember reading that a bloke in the states managed to sell a decrepit old aircraft, for a vast sum of money, to a certain company purely on the basis of its reg - N1KE
