If you purchased separate ANSYS Academic Research and ANSYS Academic Teaching licenses on the same Purchase Order, then unless specified otherwise you'll receive a single license file. If you need to split those licenses into seperate license files, on different servers, then you should contact your ANSYS account manager to discuss a revised license file. I'll let others on the Student Community chime in on whether it is possible to have two seperate license files coexist on the same license server, but with each license file using its own FlexNet port number.
If you purchased a Campus Wide Solution license, then the license file can also be split betwen Teaching and Researcher licenses, but as above this is for splitting across different servers (real or virtual), but not different FlexNet ports on the same server.
Another, easier and more flexible approach to segregate Research and Teaching licenses on the same server is to use the FlexNet Options File. This approach will allow you to control access to each license increment in your license file based on username, IP address, or Host Name and provides numerous options to group users, allow, deny, reserve licenses.
I hope my reply here proves useful.