A doubled die is a doubled die no matter how minor. Whether or not it's collectible and warrants a premium value is a different issue altogether. I personally wouldn't buy any of these (or a large number of different minor die varieties) for over the value of a normal coin, which in this case is 25 cents. However, there are people who might disagree.
Secondly, for this to be placed in the same basket with errors is incorrect, both for the purpose of using correct terminology and for the purpose of being fair to collectors of each - errors and varieties. They are completely different from one another, and this is one of those cases where they cannot be compared.
MOST errors - broadstrikes, struck throughs, off-centers, clips, indents, etc., have to be very visible to carry any premium value. By nature, that's what error collectors want - something easy to see. In die varieties, however, the anomalies are very often far more subtle, yet are still (in some cases) rare and warrant hefty premiums.
Examples...if I were to come up with a single rim clip that makes only a small flat indent on the edge of the coin, most people would say, "big deal," and walk on. It's nothing, really. But find a 1946S/D cent (which requires 10X magnification just to see it) and you would have people falling over themselves to offer you $500 for the coin.
Errors and varieties are completely different things, and the sooner new collectors learn and accept the difference the sooner they are likely to understand articles, books, and the market a lot better.