Can I have Harris Geospatial FlexNet License Server and FME Server on the same computer?

Yes! You can absolutely have both on the same computer but you would need to change the default port used by the Harris License Server. By default, the Harris License Server will use Port 7070. However, FME Server needs this port to initially register our FME Engines. If you'd like to use both it's best to assign the Harris License Server to use another port. https://www.harrisgeospatial.com/Support/Self-Help-Tools/Help-Articles/Help-Articles-Detail/ArtMID/10220/ArticleID/15103/How-to-change-the-Harris-FlexNet-License-Server-Service-default-TCPIP-communication-port-number-7070-to-a-custom-value