Disregard, I found the problem. I owned the previous version of KATL, (which also had SODE jetways). When I uninstalled the original ImagineSim KATL, the uninstaller left the original jetways definition xml file in the SODE folder in C:\ProgramData
Installing the new KATL version installed the latest SODE definition xml file in the scenery’s own folder. Apparently, when the scenery was loaded, it was getting jetway definitions from both the old and new xml files, resulting in the doubling.
I deleted the old xml file from the SODE folder in C:\ProgramData, re-ran the scenery installer, and it placed the new version in the SODE folder and in the Scenery folder, and the jetways now work properly.