Your copy protection just sounds like a universal halved mutation rate for that species, assuming every gene has a duplicate error-checker version.
If you want only some genes to have copies, then it's basically regular mutation protection only for those certain genes, but you're limiting the mutation protection to either the regular mutation rate or 1/2 the regular mutation rate, if I understand you correctly.
This may be the effect of the method I described, but it was not the point I was trying to make. In essence I believe that mutation protection should be a part of the genome of the species, not some magic outside it. While I sympathise with your goal I do not like the way you want to achieve it. To me it seems you are proposing a magical shield against mutations. As said I would like to see mutation protection seated within the genome. Properly defined base pairs with the combined ability to protect against mutation may surprise us by recombining into new functions in a way magic will never.
DB has tons of "magic" in it, simply because we're simulating this on old PCs and it would be impractical to simulate every RNA, protein, and phospholipid in a real cell. That's why movement, for example, works magically, instead of simulating actual flagella, even though simulating them would allow for evolution to modify them in neat ways. So, I think we should try to port as many features from real biology in to DB as completely as possible, and one of these features is having the mutation rate as an analog gradient, which is not possible in your implementation.
However, you do have a good point, so I'll add it to the poll. Thanks!