Not at all. It is pretty obvious which aircraft are developments of other aircraft...
If so:
- Is Ta-152 is different from 190s? It is actually based on Dora
- Is 190A and 190D are different - just installed inline engine?
- So maybe we need to split 190As and 190D/Ta152 instead Fw190/Ta152 or all are the same?
- Is La-7 and La-9 same or different aircraft one all metal other all wooden - but it still continues La-7... So if LaGG-3 is same as La-7 than LaGG-3 and La-9 are the same?
- Now if Yak-1 and Yak-9/3 are the same than the same should be Yak-15, it is just an engine refit.
Where do you split the Spitfire versions between Spit 1 and Spit F.20? They all evolve from one to another.
Bottom line -
it is endless discussion.
What is probably more correctly is to split some of the "variants" that passed though entire WW2 being a one plane but actually doing a major leap.
The only planes that I can think by
your definition are "the same" are Spitfires, 109s, Yaks, 109s.
Note USAF tended to replace lines than upgrade existing variants: P-40 and F4F were removed by the middle of the war. The P-38 entered the European theater but left till the end of 1944 and were replaced with P-51D.
If you bring me data about major variants of Spitfire & 109 I think it would be better to split them - but all major variants are already in the AH on the other hand. If you have information about 109 or Spit major variant that was produced >1000 and not in AH I'll gladly add it. But again - it isn't back and white - there are lots of grays.