@Natalie Cromer …so where exactly are you seeing doubling on this coin? Cuz, frankly, I don’t see any. Neither Variety Vista nor Wexler list any varieties for SBA 1980-D.
These were rife with die deterioration. And like Spark said there weren't many variety's. The only one known is very minor and on the 99.
I have to agree, I don't see any doubling either. Maybe you can note where you are seeing it to help us look closer.