Once that is done you can safety remove the orphan control files.
startup nomount sqlplus '/ AS SYSDBA' SQL> alter system set control_files='+REDO1A/eistst_sby/controlfile/current.539.790167061', '+REDO1B/eistst_sby/controlfile/current.538.790167061' scope=spfile; SQL> startup mount
My thought is the duplicate has it set to all these extra copies. So if you don't change the database will fail when you try to mount it. By setting it you separate the control files you want form the ones you don't want.
Why do i need to change control_files parameter?
If one of those files is missing the database won't start. So you need to set this and then remove.
show parameter control_files;The output is: