DR file in Veritas\B2D folder on RDX backup disk

We're running Backup Exec 2012 Small Business Edition on our SBS2011 server and performing nightly back ups onto RDX disks.

As I understand it we need to keep a copy of the .DR file generated during backup in order for SDR to work, however I notice that BE saves a .DR file into E:\Veritas\B2D (where E: is the RDX disk). Is this file suitable for SDR? Does this mean we don't need to worry about making a copy of the .DR file in C:\Program Files\Symantec\Backup Exec\sdr\Data\ or are the files on C: and on E: for different purposes? I notice that while the .DR file on any given RDX disk (E: drive) is about 6 MB, the .DR file on C: is about 2 MB.

Thanks for any clarification you can provide.