RMAN restore to ASM, why it create aliases in ASM

scenario 1:

===================

db_name=orcl

db_unique_name=noncdb

db_file_name_convert=

db_create_file_dest=

script and output:

================

RMAN> run

{

startup nomount pfile='/home/oracle/initorcl.ora';

restore controlfile from '/u02/oem13c/backup/orcl_04s7akt6_1_1';

alter database mount;

set NEWNAME FOR DATAFILE 1 TO '+FLASH/NONCDB/DATAFILE/system01.dbf';

set NEWNAME FOR DATAFILE 2 TO '+FLASH/NONCDB/DATAFILE/sysaux01.dbf';

set NEWNAME FOR DATAFILE 3 TO '+FLASH/NONCDB/DATAFILE/undotbs01.dbf';

set NEWNAME FOR DATAFILE 4 TO '+FLASH/NONCDB/DATAFILE/users01.dbf';

restore database;

switch datafile all;

select name from v$datafile;

shutdown immediate;