Can Common user and local user name be same in oracle 12c?

In a multitenant environment, a common user is a database user whose identity and password are known in the root and in every existing and future pluggable database (PDB).

Hence common user and local user name cannot be same.

Lets proof this satement

SQL> alter system set  "_common_user_prefix"='' scope=spfile;

System altered.

SQL> create pfile from spfile;

File created.

SQL> shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

In pfile

ora12c._common_user_prefix=''

SQL> startup pfile='C:\app\XXXXXX\product\12.1.0\dbhome_1\database\INITora12c.ORA';

ORACLE instance started.

Total System Global Area 1068937216 bytes

Fixed Size                  2410864 bytes

Variable Size             666896016 bytes

Database Buffers          394264576 bytes

Redo Buffers                5365760 bytes

Database mounted.

Database opened.

SQL>

SQL>

SQL> show con_name

CON_NAME

------------------------------

CDB$ROOT

SQL> create user demo identified by demo;

User created.

SQL> select name,open_mode from v$pdbs;

NAME                           OPEN_MODE

------------------------------ ----------

PDB$SEED                       READ ONLY

PDBORA12C                      MOUNTED

SUBUPDB                        MOUNTED

TEST                           READ WRITE

SQL> alter session set container=TEST;

Session altered.

SQL> show con_name

CON_NAME

------------------------------

TEST

SQL> create user demo identified by demo;

create user demo identified by demo

            *

ERROR at line 1:

ORA-01920: user name 'DEMO' conflicts with another user or role name

SQL> show con_name

CON_NAME

------------------------------

TEST

SQL> create user hello identified by hello;

User created.

SQL> show con_name

CON_NAME

------------------------------

CDB$ROOT

SQL> create user hello identified by hello;

create user hello identified by hello

*

ERROR at line 1:

ORA-65048: error encountered when processing the current DDL statement in

pluggable database TEST

ORA-01920: user name 'HELLO' conflicts with another user or role name