What is BACKUP.RAW file?

[jaxx]

Hi everyone!
After my last shooting raw video on my 5d mark3 I detected BACKUP.RAW files (one per card) among other regular raw files.
And another thing: some of my raw files did not open with raw2dng program
So i wonder if BACKUP.RAW file have somthing to do wath this? How can I solve the problem of no opening with raw2dng?
And anyway what for BACKUP.RAW file?

[Midphase]

My advice would be not to delete anything off of the card until you have converted all of the files you need into a usable format.

Not sure what backup.raw does exactly, but when in doubt I leave it alone.