I think the best person to explain that may be @dougsmit he seems to have the knack for it. I'm the type of "I can explain it to you but I can't make you understand it". In other words I have a hard time choosing the right words to explain my thoughts. I'm pretty sure they are unofficial and the reverses are from other denari or coins. Like the Geta there that reverse comes from one of Sept. Sev's (his fathers), right off hand I can't give a reference to which. I also know there is no official list or reference such as RIC or RSC for them.