Two PhDs, a correspondent and a first author can count. In academia, the correspondent and the first author are both very important roles, and they will be included in the list of paper authors. Correspondent usually refers to the person who is responsible for communicating with the outside world, organizing the writing of papers and coordinating the relationship between authors in the research process, while the first author refers to the author who has made great contributions in the research process. A paper usually has only one correspondent and one first author. If both doctors are correspondence authors and first authors, they can be included in the list of paper authors together.