Is the patent certificate generally only issued to the first applicant? Or have they all issued patent certificates?

A patent has only one patent certificate, but it is not issued to one applicant, but all applicants have it. Moreover, if there is no contract between applicants, the right to dispose of the patent right is the same for each applicant, whether you are the first applicant or the tenth applicant. So you don't have to worry about not having a certificate at hand.