DDD - Die Deterioration doubling Worthless doubling http://www.error-ref.com/die-deterioration-doubling-incuse/
According to an article I read this penny is known to have doubling that is why I posted it. But after reading the URL you posted you are the expert
Doubling, but not a doubled die. There are numerous causes of doubling on our coinage. 99.875% of doubling is common mechanical/ejection/machine doubling (take your pick of the exact word)
Quickly want to show you the 1978 penny. I assume you think I should know this (errors) by now but I don't.
Looks like die deterioration doubling around the date. I don't see anything else. The following links give nice explanations of how to spot a true doubled die and the characteristics of MD and DDD. If you start taking the time to study them, things will start to make sense http://www.doubleddie.com/58222.html - Doubled die process and characteristics http://www.doubleddie.com/144801.html - Worthless doubling