Analemmatic dials

Callaway Gardens, Pine Mountain (Georgia, USA)

Double dates? What intrigues me here are the two rows of tiles where one would expect the date line. No separate date lines for summer and winter, for sure. Perhaps for Eastern and Central Time? The time zone border is nearby.
No gnomonic data given.


Website: NASS Registry
Code NASS: #386
Location: 32.9° N, 84.8° W
Design: ?
Inauguration: ?