Domains changing owners and parking

I have a question,lets say person X own some domain and park it at NameDrive, then that some1 sells this domain to person Y,

and then person Y also put this domain for parking at NameDrive.
While person X hasn't deleted this domain from his NameDrive portfolio, so the question is will he still get money for it

even if he doesn't own the domain any more? will they both be getting the money for the same domain?
I mean they both has this domain in their portfolios, and the domains DNS are NameDrive's, so how NameDrive can know who is

the real owner?