Names and Planes
I suspect that the reason the Lancaster was not called the 'Manchester Mk 2' was due to the former machines history (engine issues) and consequent wish to forget it.
The name only becomes an issue when/if a particular aircraft achieves notoriety,one way or another.
Nowadays we would call it 'Branding' and someone would have spent considerable time and money researching the effect;however in the real world of fighting aircraft the actual reputation will always be the key to how it is seen by the public 'at the time';the name will then assume a fond memory 'or otherwise'.