My listener configuration produces multiple instances of the same db

Database 19.3 Standard Edition 2 on Oracle Linux 8.8 (vm on ESXi 8)

Initially, my listener.ora had only a simple statement:

LISTENER =

 (ADDRESS_LIST =

    (ADDRESS= (PROTOCOL= TCP)(Host=<hostname>)(Port= 1521))

 )

I wanted to register multiple databases to the single LISTENER, but merely naming them in tnsnames.ora didn't give me access via sqlplus. I edited listener.ora to list the databases.

SID_LIST_LISTENER =

 (SID_LIST =

   (SID_DESC =

     (GLOBAL_DBNAME = mriTEST)

     (ORACLE_HOME = /u01/app/oracle/product/19.0.0/dbhome_1)

     (SID_NAME = mriTEST)

   )

   (SID_DESC =

     (GLOBAL_DBNAME = mri10)

     (ORACLE_HOME = /u01/app/oracle/product/19.0.0/dbhome_1)

     (SID_NAME = mri10)

   )

 )

LISTENER =

 (DESCRIPTION_LIST =

   (DESCRIPTION =

     (ADDRESS_LIST =

       (ADDRESS = (PROTOCOL = TCP)(HOST = <hostname>)(PORT = 1521))