There might be some sales gain but not double though.
Kpop fans buy a million versions at a time and that’s where the bulk of the sales comes from.
I never said anything about doubling sales figures, but two albums dropping in consecutive months lowers the ceiling of each album's potential sales. This isn't conjecture. I'm in the fandom. A lot of Bunnies had to decide which album to spend money on, especially if they want the sales to count towards music shows.
How many teens can just throw a hundred bucks or more down in consecutive months?