To install another Gateway on the same server you need to:

1. Copy paste the TimeXtender Gateway folder from C:\Program Files(x86)\Exmon Gateway to for example C:\Program Files(x86)\TimeXtender Gateway2.
2. Inside TimeXtender Gateway2, delete both ExmonClientConfig.config and ExmonDataConnector.exe.config
3. Copy paste ExmonDataConnector.exe.config.template and rename it to ExmonDataConnector.exe.config