This is done on projects like VeraCrypt with hidden containers to give you plausible deniability - one password opens the decoy container and another opens the real one. Of course this means a ton of wasted space on the disk, and as soon as you boot the decoy container it starts desytroying hidden container data. And also there's apparently ways to detect hidden containers if this is to be believed:

https://ro.uow.edu.au/cgi/viewcontent.cgi?referer=&httpsredi...

Wildly unrealistic but it exists.