文档解释
ORA-01566: file specified more than once in ALTER DATABASE
Cause: The list of files supplied to the command contained at least one duplicate.
Action: Remove the duplicate file specification and retry.
ORA-01566：在ALTER DATABASE中指定的文件多次出现
官方解释
ORA-01566: file specified more than once in ALTER DATABASE statement
Cause: The same file was specified more than once in an ALTER DATABASE statement.
Action: Make sure that a file is only listed once in each statement.
常见案例
典型的ORA-01566错误可能是由于用户在ALTER DATABASE命令中指定了多个相同的数据文件时而发生的：
SQL> alter database add alternate datafile ‘/u01/oradata/orcl/users02.dbf’ reuse;
ORA-01566: file specified more than once in ALTER DATABASE statement
正常处理方法及步骤
要解决这个错误，需要保证每个命令只列出一次文件名，而不是多次列出同一个文件：
SQL> alter database add alternate datafile ‘/u01/oradata/orcl/users02.dbf’ reuse;
数据库已更新。
