For ODBC Driver for Teradata starting with 15.10.10.00, for UNIX bundle, Windows, and OS X Suites, multiple releases can co-exist on the same system. For example, 15.10.10.00, 16.10.00.00 and later versions can co-exist on the system at the same time.
If a specific version of the driver that is not the active TTU version is needed by an application, then the ODBCINI environment variable must be set to <InstallDir>/Teradata/client/<desired version>/odbc_32/odbc.ini for 32 bit or <InstallDir>/Teradata/client/odbc_64/odbc.ini for 64-bit, and that odbc.ini file must be updated accordingly.
Another option is to use the .env files provided for each OS. The .env files are located in <prefix>/teradata/client/16.20/<etc>.
The .env file can be sourced in a terminal window so that release is active in that session.