local user on a plugged-in pdb conflicts with common user on target cdb

2 cdbs: cdb1 & cdb3
cdb3 contains a pdb named pdb31
Now i need to unplug pdb31 from cdb3 and plug it into cdb1 as pdb31_copy1

--on cdb1
alter session set pdb_file_name_convert='+CDB2DG/pdb31_','/oradata1/pdb31_copy1/pdb31_copy1_';

--on cdb3
alter pluggable database pdb31 close immediate;
alter pluggable database pdb31 unplug into '/home/oracle/xmlfile/pdb31.xml';
select * from v$pdbs;
select * from cdb_pdbs;

--on cdb1 ,when i open pdb31_copy1, it informs an error
create pluggable database pdb31_copy1 using '/home/oracle/xmlfile/pdb31.xml' copy tempfile reuse;