Need Help Defining Roman Coin: Faustina Augusta

In ancients, you very rarely will find coins that look "exactly the same" as yours. In fact, finding one that does look exactly the same would be cause for concern, since it would be reasonably likely you'd have a fake in such a circumstance. Minor varieties such as positioning of letters or the shape of attributes such as the altar often aren't even mentioned in the catalogues. Where the legends break (DIVAAVGVS TAFAVSTINA versus DIVAAVGVSTA FAVSTINA, for example) is a more common diagnostic for separating varieties.

Unfortunately, Wildwinds is down for me right now and I'm away from my reference books, but it appears your coin is definitely Faustina Senior.