SQL Server 2005 Enterprise Edition and Development Edition supports mirrored backup. Mirroring a media set increases backup reliability by adding redundancy of backup media which effectively reduces the impact of backup-device failing. While taking backup of database, same backup is taken on multiple media or locations.
T-SQL code to take Mirrored Backup :
BACKUP DATABASE AdventureWorks
TO DISK = 'c:\AdventureWorksBackup.bak'
TO DISK = 'd:\AdventureWorksBackupCopy.bak'
Above script will create two backups at two different locations, if backup of one location is corrupted backup from another location will work fine.
Reference : Pinal Dave (http://blog.SQLAuthority.com)