It's worth noting that this is a classic problem in letterpress shops -- if you get careless and forget that the letters should be reading backward it's easy to substitute b for d, p for q, and so on. L for J, or I for either, is another case of the same thing.
It could be worse. Gothic fonts are notorious for having capital letters that are hard to read, leading to things like the "Saint Ioseph Gazette" going for two decades before someone noticed that the J had turned into an I.
The real question is: Do they take the solution the Post Office does when defective stamps escape, and crank out a bunch of equally defective ones to kill the unintended collectors' value and avoid the temptation for staff to sell additional "rare" copies under the table at hugely inflated prices, or do they think they can recover enough to keep that from becoming an issue? Depends, I suppose, on how incorruptable they think everyone they're working with will be.