How can two or more applicants apply for a patent for the same invention and creation on the same day?

Only one patent can be granted for the same invention.

Where two or more applicants apply for a patent for the same invention and creation on the same day as stipulated in the Patent Law, they shall determine the applicants through consultation after receiving the notice from the Patent Office: where two or more applicants apply for a patent for the same invention and creation respectively,

The patent right is granted to the person who applies first.