I'm sorry, I went back and read more carefully. I see what you mean, but I think the 5 suffered a hit that just moved some of the metal.
The copper is a soft metal. It looks like it's doubled but it took a hit and some of the metal shifted to give it the effect you are seeing. Keep looking.
This coin is worn. That's one reason. Mechanical doubling, ejection double, machine doubling (I think are all the same thing) is another possibility. When the die gets old and has punched hundreds of thousands of coins the details aren't crisp anymore. Another possibility. As for doubled dies, I would stick with the list of known dates. Every date is not a doubled die.
