文档解释
ORA-00251: LOG_ARCHIVE_DUPLEX_DEST cannot be the same destination as string string
Cause: The destination specified by the LOG_ARCHIVE_DUPLEX_DEST parameter is the same as the destination specified by an ALTER SYSTEM ARCHIVE LOG START TO command.
Action: Specify a different destination for parameter LOG_ARCHIVE_DUPLEX_DEST, or specify a different destination with the ALTER SYSTEM command.
ORA-00251错误代表日志归档重复目标（LOG_ARCHIVE_DUPLEX_DEST）不能与两个参数（通常是LOG_ARCHIVE_DEST_1和LOG_ARCHIVE_DEST_2）指定的目标相同。
官方解释
ORA-00251: LOG_ARCHIVE_DUPLEX_DEST can not be the same destination as the string string
Cause: The LOG_ARCHIVE_DUPLEX_DEST parameter had the same destination as a LOG_ARCHIVE_DEST_n parameter.
Action: Set the two destination parameters to different destinations.
常见案例
当将LOG_ARCHIVE_DUPLEX_DEST参数设置为与LOG_ARCHIVE_DEST_n参数指定的目标相同时，可能会出现ORA-00251错误。
正常处理方法及步骤
解决ORA-00251错误的正常处理方法是更改 LOG_ARCHIVE_DUPLEX_DEST 和 LOG_ARCHIVE_DEST_n参数，以使两个参数指定不同的目标。
