Q: Can multiple submissions to a journal have a common contact author?
At my institution, whenever we submit a paper, the contact author has to be our supervisor. My field is very niche and there are very few journals in this field. Hence, all the members in our lab submit manuscript to only two journals. We have submitted 3 manuscripts with different first authors but the same contact author to one particular journal. Though the topics are quite different, I still feel worried. Is this fine? How to solve this issue?
Having the same contact author for more than one paper should not be a problem if the submissions are distinctly different. These days, most papers are multi-author papers. As long as the topics of the papers are completely different, it does not matter if one or more authors are the same. In your case, even the first author of each paper is different, so there is no reason to worry. Like you, the journal editor must also be aware that this is a niche field and has very few journals. The editor might also be aware that certain insitutions have the system of assigning the supervior as the contact author. Hence he/she will definitely understand why multiple papers with the same contact author are being submitted to his/her journal.