Is there a reason why Let's Go Pikachu & Eevee are being counted as separate games?

[SecondWar]

Green098 said:

Machina said:
The upside is that it'll be interesting the see the split between the two physical versions in the meantime, and then at the end of January we'll probably create a unified version and shift the total over to that, deleting the separate versions. Until then you'll just have to manually combine them when comparing to previous Pokemon games xD

I have a feeling it's not going to go as well for Eevee as it will for Pikachu...

Lol at that picture. But yeah, I think the general trend is the former title always tend to sell better than the latter one. Although for some reason I think only one that bucked that trend was X (don't quote me on that)