>        3) Oracle Specific
>                Do not use RMAN's Multiplexing in RMAN will combine 4
>Channels together and the backup data then will be unique every time
thus
>not allowing for                        de-duping)
>                Use the File Seq=1 (Then run multiple channels)

I don't see how this would affect de-duplication if your de-dupe product
knows what it's doing.  Every block coming into the device should be
compared to every other block ever seen by the device.  So combining
multiple files together using Oracle multiplexing shouldn't affect
de-dupe.

Did you test this, or see it in the docs somewhere?  Was this true for
multiple de-dupe vendors, or just the one you chose?