(1) make sure you have enough of the correct Genesys licenses.
(2) your DB is of a high enough spec.
(3) the apps v6.5 v v7.2 will need to use different port numbers
(4) your switch supports 2 TServers simultaneously.
(5) keep the install locations separate.
Unless this is a very small test environement, I wouldn’t recommend doing what you want. Even then using the same server will be a false economy.