My research, which is extremely controversial, indicates that Dickens didn't write "A Christmas Carol." Rather, he hurriedly revised an existing manuscript to get it ready for publication in time for the 1843 Christmas season, and to avoid impending debt. The original was written by American authors Mathew Franklin Whittier, and his wife, Abby Poyen Whittier. To answer your question specifically, my research suggests that the next-to-last paragraph of that book was originally the conclusion; and that Dickens revised it by adding the last paragraph. If you look at the next-to-last paragraph closely, the viewpoint expressed in it is not consistent with a famous, successful author; however, it is a precise match for Mathew, a humorist, and Abby, who had been persecuted by the townspeople as a witch. It suggests that the narrator is accustomed to being laughed at and misunderstood, and laughs it off. The paragraph that Dickens added at the end, would be inconsistent with Mathew and Abby, who believed in Spiritualism--it would, however, be consistent with Dickens, who thought of the entire novel as a "ghost story," and who was a skeptic in such matters. Only Dickens would have narrated that Scrooge had no further contact with spirits, as though he was abstaining from alcohol.
I note that the instructions below say to avoid "making statements based on opinion." I do have a great deal of evidence for my conclusions, but I hardly have room to give them, here. I've substantiated my answer with as much logical evidence as it seemed fit to provide in this format.