Thomas,
Duncan’s Ritual is not, and never was, the official ritual of any Grand Lodge. My information is that it was published to be a sort of generic ritual which would help those wanting to learn the ritual used in their lodge, wherever that might be. It supposedly pieces together the wording and floorwork which is most commonly used among various Grand Lodges.
Unlike England, where no standard ritual working is mandated for use by lodges, in the USA every Grand Lodge that I know of has an official working, or ritual, which must be used by all lodges. Moreover, they have an officer, usually called the Grand Lecturer, whose duty it is to see that the standard work is taught and practiced as close to verbatim as possible, which he does through Deputy Grand Lecturers who conduct schools or lodges of instruction.
For instance, the Constitution of the GL of MD states that the ritual working for use in Maryland lodges is that of the Baltimore Convention of 1843. No change in the ritual working can be made or allowed unless this provision of the Constitution is deleted or changed. Hence, in Maryland, we have been using the same work, with no changes, since 1843 and there is no chance that enough GL members could be found to support any change. We have one lodge that works in the German language; they use the same ritual translated very carefully into German.
So the idea of some lodge deciding to use Duncan’s as their ritual is a non-starter. If you want to learn the work as it is practiced in your jurisdiction, Duncan’s won’t be exactly like it and this could cause you to learn what would be incorrect work in your jurisdiction. The only way to learn the work and learn it right is to attend lodge and witness the work as often as possible, paying attention and trying to memorize it as you listen. This can be done; I did it myself as a young officer starting out. When you are advancing through the officer line, you can always polish up and make sure you have it right by enlisting the help of an expert PM or other brother.