@Ashraf, the CM Environment ID is stored in the Topology Manager Database. So as long as your two clustered CM servers are connecting to the same Topology Manager database, it should have the same CM Environment ID.
The %TRIDION_HOME%\Topology Manager\web\web.config%TRIDION_HOME%\Topology Manager\web\web.config
contains the database setting
Note: The database setting is encrypted so you will need to decrypt it before seeing the info.