The identical date of sale suggest that these two were together somewhere.
It could just be that the paperwork had been badly noted on the old unit records or that this clerk transposed the numbers - but he should have known the numbers well enough to realise that the last two digits should be identical ? These clerks were enthusiasts, weren't they ?
It could be that fuel tanks had become swapped during service or, horror of horrors, that the engines had been swapped over and it is actually the engine numbers that are noted in the key card records rather than the frames, making all this research worthless ?
That row heading referring to Armoured vehicle engine numbers or 'B' vehicle chassis numbers worries me quite a bit.
The 2 bikes had consecutive postwar registration numbers and were sold at the same time maybe 6 years later, does that mean that they stayed in the same depot together all that time?
Some bikes have turned up in original paint with annual inspection dates stencilled on the petrol tanks, but would the tank have to be removed for this inspection? it seems unlikely.