Can I have more than one db_recovery_file_dest?
You can have only one Flash Recovery Area defined by the db_recovery_file_dest. If you do not want to use one directory then you can go for ASM where you can create and use a disk group that can span multiple disks/partitions.

You can also go for LVM if you use Linux. This is simular to ASM. Create a physical group that contains multiple partitions. On that physical group you create a logical volume and mount it to a directory.