When is a Backup not a backup?

Writing in his blog, Genealogy's Star, James Tanner argues the point that hitting the 'Backup' button on Personal Ancestral File (PAF) does not really solve the problem of providing a secure second copy of the PAF file, as, if the hard drive goes, both the main and the backup files are lost.

I suppose he is not wrong, but is he correct to suggest this is not a good policy to follow? James goes on the suggest that the backup should be to a separate external storage device, perhaps a portable flash drive.

I am a Legacy user, and the same options are available. But as anyone who has had multiple files open, and entered data erroneously onto the wrong file, or even added a duplicate Gedcom file, resulting in many wrong entries, the option to go back to an easily accessible backup copy is attractive.

There is one point that he make which I fully endorse - give each backup copy a different name, perhaps including the date, so that there are clear return points to go to. One again I speak from experience - and it was not a good one!