Which two are true about RMAN duplexed backup sets? (Choose two.) 

Answer options:

A. A duplexed backup set uses the same number of SBT channels as a non-duplexed backup set for the same number of files.
B. A non-duplexed backup set written to disk can be duplexed to disk by backing up the backup set that is already on disk.
C. A non-duplexed backup set written to SBT can be duplexed to tape by backing up the backup set that is already on tape.
D. A non-duplexed backup set written to disk can be duplexed to tape by backing up the backup set that is already on disk.
E. A non-duplexed backup set written to SBT can be duplexed to disk by backing up the backup set that is already on tape.
F. A duplexed backup set always uses twice as many SBT channels as a non-duplexed backup set for the same number of files.

DF