Assuming you are using the current version of the program, and you haven't edited any of the default GSX vehicle files, there are no duplicates title names in GSX.
You can verify this is the case, by checking the SIM.CFG file in the SimObjects\Misc\FSDT_Pushback_02 folder, and you'll see there's only ONE object with a title "FSDT_Pushback_02_AQ". Also, no other objects with the same title are found in all SIM.CFGs in the whole Simobject folder so, there are surely no duplicates names in GSX.
Check your Prepar3D.cfg file, under the [Main] section, and see if you have duplicates lines pointing to the SimObjects\Misc folder.