So I have a tiny little AE4 Valentinian II. It's actually in decent shape for an AE4. DN VALENTINIANVS PF AVG; diademed, draped, and cuirassed bust right. VICTORIA AVGGG; two Victories facing each other, holding wreaths. SMAQS; RIC IX Aquileia 47a The -GGG indicates that three augusti were reigning at the time this coin was struck, ca. 383-388 A.D. Candidates for the other two augusti at this chaotic time: Gratian (375-383) Theodosius I (Eastern Emperor, 379-392) Magnus Maximus (384-388) Flavius Victor (384-388) Who are the 3 augusti implied on this coin? I assume Valentinian II, Theodosius I, and who else?
My bet is that since it started being struck in 383, it's Gratian and Theo I, and then they just continued to strike it after the fact... no need to add another G or two in 384 and on. Just my own speculation.
http://augustuscoins.com/ed/ricix/type33.html Our own Valentinian of Coin Talk has a page on this and most other questions from this period.
Warren says Valentinian II, Theodosius, and Arcadius. Did not expect the latter. Thanks to Doug for the heads up, and to Warren (@Valentinian) for the page and research.