Help needed with 5 cent varieties

[Hercules]

There's some footnotes in McDonald's for 1997, 1998, 2002, 2003, 2004, 2005 and 2006.
From the pictures I've seen they're pretty similar.

There aren't any varieties for those years; i.e. just one obverse and one reverse for each of those years.

So what is the extra type mentioned in McDonald's? I've never looked out for them but I'm guessing it's something to do with the strike (lots of 20c pieces seem to have this sort of double-struck SD which makes the lettering look much fatter).

I've tried looking for those ones before, but I cannot tell the difference between them – even under a microscope. Perhaps the person who discovered them was using an electron microscope. :dontknow:

[Mister T]

I figured that it's not a real design change as it seems to have come and gone and never been 'adopted' (i.e. become the dominant design).
Someone on CCF has looked out and found them but I haven't really bothered.

[Nevol]

Another one for noodlers to keep an eye out for now is the 2005 5c Flamingo coin. 

One of the members on CCF has posted pictures of one. 
https://www.coincommunity.com/forum/topic.asp?TOPIC_ID=325414