i could almost find nothing on information Maximianus Herculius, 286-305. Follis, 305-306 Aquileia. my coin/ vendor pictures Rv. VIRTVS AVGG ET CAESS NN https://www.acsearch.info/search.html?term=Maximianus Aquileia horse&category=1-2&en=1&de=1&fr=1&it=1&es=1&ot=1&images=1¤cy=usd&thesaurus=1&order=0&company http://www.forumancientcoins.com/gallery/thumbnails.php i could not find one type
Your coin appears to be RIC vol.VI, Aquileia #66b. It's listed as rare, but as you've already discovered, there's a few variants out there, such as the three soldiers being trampled shown above, different reverse inscription breaks, and a later version with IMP C MAXIMIANVS P F AVG.