Redundancy is a good thing.

(While we're on the subject, I've considered Les' argument that compressed files take less space on the disk and are therefore less likely to be corrupted before.  It's true, but like dedupe errors, it's just *one* possible failure--and to me, not a very likely one.  It's not one worth defending against by *itself*.  Having uncompressed files makes, e.g., scanning a badly scrambled filesystem for salvagable data *much* easier.

 When it comes to backup, I will almost *always* choose simple over fancy, even if fancy gives me other advantages but not additional safety.)