sorry, but that looks to me like someone got ripped off, not everyone knows what die deterioration is, especially new collectors and stating "strong doubled date" is misleading, i'll bet you laugh all the way to the bank every time you sell one of those....
you automatically ASSUME they didn't know what it was but you can not be SURE. and if they did get ripped off as you put it then it's only because they were to lazy to learn about what they were buying before buying it. it was a strong doubled date. I never intentionally mis led anyone to anything.
You definitely scammed someone. If you sold this coin to someone you scammed them. Plain and simple. It's not a doubled die. This is rather annoying to see. It's not even die deteration doubling it's a plating disturbance doubling. http://www.error-ref.com/other-forms-of-doubling/ And that's exactly what you have. You might want to know what the heck you are selling before you go and scam people and not even know you scammed them, and tell us knowledgeable people that we don't know what we talking about. COMPLETELY disgraceful