Here are three VLPP's from Siscia. All are RIC 52, the obverse legend has MAX in it. Constantine was awarded this title by the Roman senate shortly after his defeat of Maxentius in A.D. 313. This coin has the first use of the title MAX in the East for Constantine, and it is the only time it was used for the Siscia VLPP.
The styles on these three coins vary greatly and I do not believe all are official issues. I have no doubt that the first coin is official. I also have no doubt that the second coin is unofficial. The third coin is tricky, it looks pretty good; but there are a few things that make me lean towards unoffficial.