As I understand would only need to change the ports if QlikView and Qlik Sense where running on the same machine, but according to the Qlik Sense documentation it is not possible to install Qlik Sense on a machine with QlikView Server already installed.
While there are ways of installing Qlik Sense Enterprise and QlikView Server on the same machine, that would not be supported in any way. Consider that the two softwares would conflict over resources, making the server instable.
No, issue, of course, if you are talking about the two desktop clients (as long as you don't run them at the same time performing reloads or working with large documents).
Daniele - Senior Technical Support Engineer & SaaS Support Coordinator at Qlik If a post helps to resolve your issue, please accept it as a Solution.