If different versions of tdwallet are installed on the same system, then all versions have to be installed at the same prefix. This is to enable all versions of tdwallet installed on the same system to share the wallet data. If tdwallet 15.10 is installed at prefix /abc then the install path will be /abc/teradata/client/15.10. If tdwallet 16.20 is then installed on the same system then the prefix has to be the same as the installed 15.10 tdwallet, which implies that the install path for 16.20 tdwallet will be /abc/teradata/client/16.20.