I'd like to resurrect this post and ask a question about this coin.
I've read Victor's fine discussion of this "Hercules Farnese" post here:
http://www.constantinethegreatcoins.com/HERCVLI/The discussion raises the issue of Tetrarchic iconography and its relationship to this coin (i.e., Western emperors such as Constantine were of the "Herculian" house.)
Since this coin was struck only in Eastern mints and was much more common for Maximinus II (and at mints controlled by him, I think?), it seems that Hercules more reflects Maximinus II's affinity for the god rather than an intentional evocation of Tetrarchic iconography. I'm thinking Maximinus II liked the Hercules reverse and simply struck it for Constantine and Licinius in 312 during a brief moment when an alliance seemed possible. With that having been said, perhaps he was "honoring" the other (Herculian) house as part of this alliance hope? I'm just not sure how much Tetrarchic iconography plays into the choice of an Eastern emperor to strike a Hercules coin. Would love to hear some idle speculation.
BTW, I snagged one of these years ago off eBay. I was surprised to see it at the NOT IN RIC site. I guess Lech does his homework:
http://www.forumancientcoins.com/notinric/6nic-75_d.html