Back in the 90s, my mom had a '79 hatchback with the 2.8, but with dual exhaust tips. Was this uncommon?

Title.

I never see these cars anymore, but even back then I remember any Mustang from that year and had the 2.8 badges only had a single exhaust tip.

I doubt it was a true dual exhaust, but again, none ever seen on other similar vehicles.

She picked it up in the early 90s. Was it actually a factory option? Would it have been a dealer option? Would a prior owner been crazy enough to custom it?